diff --git a/main/account_switcher.ts b/main/account_switcher.ts
new file mode 100644
index 0000000..f3f62e6
--- /dev/null
+++ b/main/account_switcher.ts
@@ -0,0 +1,61 @@
+import {EventEmitter} from 'events';
+import {Menu, MenuItem} from 'electron';
+import log from './log';
+import {Account} from './config';
+
+export function partitionForAccount(account: Account) {
+    return `persist:mstdn:${account.name}:${account.host}`;
+}
+
+export default class AccountSwitcher extends EventEmitter {
+    accounts: Account[];
+    current: Account;
+
+    constructor(accounts: Account[]) {
+        super();
+        const submenu = [] as Electron.MenuItemOptions[];
+
+        for (const account of accounts.filter(a => a.name !== '')) {
+            let name = account.name;
+            if (!name.startsWith('@')) {
+                name = '@' + name;
+            }
+            name += '@' + account.host;
+            submenu.push({
+                label: name,
+                type: 'radio',
+                checked: false,
+                click: () => this.switchTo(account),
+            });
+        }
+
+        this.accounts = accounts;
+        if (accounts.length === 0) {
+            return;
+        }
+
+        submenu[0].checked = true;
+        this.current = accounts[0];
+
+        const item = new MenuItem({
+            label: 'Accounts',
+            type: 'submenu',
+            submenu,
+        });
+
+        const menu = Menu.getApplicationMenu();
+        // Insert item before 'Help'
+        menu.insert(menu.items.length - 1, item);
+        Menu.setApplicationMenu(menu);
+    }
+
+    switchTo(account: Account) {
+        if (this.current.name === account.name && this.current.host === account.host) {
+            log.debug('Current account is already @' + account.name);
+            return;
+        }
+        log.debug('Switch to account', account);
+        this.emit('switch', account, this.current);
+        this.current = account;
+    }
+}
diff --git a/main/app.ts b/main/app.ts
index a7683ed..c413cb5 100644
--- a/main/app.ts
+++ b/main/app.ts
@@ -1,205 +1,52 @@
 import * as path from 'path';
-import {app, BrowserWindow, globalShortcut, Tray, shell, dialog, Menu} from 'electron';
-import windowState = require('electron-window-state');
-import * as menubar from 'menubar';
+import {app, Menu, globalShortcut} from 'electron';
 import log from './log';
 import {Config, Account} from './config';
+import AccountSwitcher from './account_switcher';
+import defaultMenu from './default_menu';
+import Window from './window';
 
-const IS_DEBUG = process.env.NODE_ENV === 'development';
 const IS_DARWIN = process.platform === 'darwin';
 const APP_ICON = path.join(__dirname, '..', 'resources', 'icon', 'icon.png');
-const PRELOAD_JS = path.join(__dirname, '..', 'renderer', 'preload.js');
 
 export class App {
-    private account: Account;
+    private switcher: AccountSwitcher;
 
-    constructor(private win: Electron.BrowserWindow, private config: Config) {
+    constructor(private win: Window, private config: Config) {
         if (config.accounts.length === 0) {
             throw new Error('No account found. Please check the config.');
         }
-        this.account = this.config.accounts[0];
-    }
-
-    open() {
-        if (!IS_DARWIN) {
-            // Users can still access menu bar with pressing Alt key.
-            this.win.setMenu(Menu.getApplicationMenu());
+        if (IS_DARWIN) {
+            app.dock.setIcon(APP_ICON);
         }
+        Menu.setApplicationMenu(defaultMenu());
+        this.switcher = new AccountSwitcher(this.config.accounts);
+        this.switcher.on('switch', this.onAccountSwitch);
+    }
 
-        this.win.webContents.on('dom-ready', () => {
-            this.win.show();
-        });
-        this.win.loadURL(`https://${this.account.host}${this.account.default_page}`);
-        this.win.webContents.on('will-navigate', (e, url) => {
-            if (!url.startsWith(`https://${this.account.host}`)) {
-                e.preventDefault();
-                shell.openExternal(url);
-            }
-        });
-        this.win.webContents.on('new-window', (e, url) => {
-            e.preventDefault();
-            shell.openExternal(url);
-        });
-        this.win.webContents.session.setPermissionRequestHandler((contents, permission, callback) => {
-            if (permission !== 'geolocation' && permission !== 'media') {
-                // Granted
-                callback(true);
-                return;
-            }
+    start() {
+        const a = this.switcher.current;
+        const url = `https://${a.host}${a.default_page}`;
+        this.win.open(url);
+        log.debug('Application started', a, url);
+    }
 
-            dialog.showMessageBox({
-                type: 'question',
-                buttons: ['Accept', 'Reject'],
-                message: `Permission '${permission}' is requested by ${contents.getURL()}`,
-                detail: "Please choose one of 'Accept' or 'Reject'",
-            }, (buttonIndex: number) => {
-                const granted = buttonIndex === 0;
-                callback(granted);
-            });
+    private onAccountSwitch = (next: Account) => {
+        this.win.close();
+        if (this.config.hot_key) {
+            log.debug('Disable global shortcut for switching account');
+            globalShortcut.unregister(this.config.hot_key);
+        }
+        Window.create(next, this.config, this.win.menubar) .then(win => {
+            log.debug('Window was recreated again', next);
+            this.win = win;
+            this.start();
         });
     }
 }
 
-function trayIcon(color: string) {
-    return path.join(__dirname, '..', 'resources', 'icon', `tray-icon-${
-        color === 'white' ? 'white' : 'black'
-    }@2x.png`);
-}
-
 export default function startApp(config: Config) {
-    return (config.normal_window ? startNormalWindow : startMenuBar)(config)
+    const default_account = config.accounts[0];
+    return Window.create(default_account, config)
         .then(win => new App(win, config));
 }
-
-function startNormalWindow(config: Config): Promise<Electron.BrowserWindow> {
-    log.debug('Setup a normal window');
-    return new Promise<Electron.BrowserWindow>(resolve => {
-        const state = windowState({
-            defaultWidth: 600,
-            defaultHeight: 800,
-        });
-        const win = new BrowserWindow({
-            width: state.width,
-            height: state.height,
-            x: state.x,
-            y: state.y,
-            icon: APP_ICON,
-            show: false,
-            useContentSize: true,
-            autoHideMenuBar: true,
-            webPreferences: {
-                nodeIntegration: false,
-                sandbox: true,
-                preload: PRELOAD_JS,
-            },
-        });
-        win.once('ready-to-show', () => {
-            win.show();
-        });
-        win.once('closed', () => {
-            app.quit();
-        });
-
-        if (state.isFullScreen) {
-            win.setFullScreen(true);
-        } else if (state.isMaximized) {
-            win.maximize();
-        }
-        state.manage(win);
-
-        const toggleWindow = () => {
-            if (win.isFocused()) {
-                log.debug('Toggle window: shown -> hidden');
-                if (IS_DARWIN) {
-                    app.hide();
-                } else {
-                    win.hide();
-                }
-            } else {
-                log.debug('Toggle window: hidden -> shown');
-                win.show();
-            }
-        };
-
-        win.webContents.on('dom-ready', () => {
-            log.debug('Send config to renderer procress');
-            win.webContents.send('mstdn:config', config);
-        });
-        win.webContents.once('dom-ready', () => {
-            log.debug('Normal window application was launched');
-            if (config.hot_key) {
-                globalShortcut.register(config.hot_key, toggleWindow);
-                log.debug('Hot key was set to:', config.hot_key);
-            }
-            if (IS_DEBUG) {
-                win.webContents.openDevTools({mode: 'detach'});
-            }
-        });
-
-        const normalIcon = trayIcon(config.icon_color);
-        const tray = new Tray(normalIcon);
-        tray.on('click', toggleWindow);
-        tray.on('double-click', toggleWindow);
-        if (IS_DARWIN) {
-            tray.setHighlightMode('never');
-            app.dock.setIcon(APP_ICON);
-        }
-
-        resolve(win);
-    });
-}
-
-function startMenuBar(config: Config): Promise<Electron.BrowserWindow> {
-    log.debug('Setup a menubar window');
-    return new Promise<Electron.BrowserWindow>(resolve => {
-        const state = windowState({
-            defaultWidth: 350,
-            defaultHeight: 420,
-        });
-        const icon = trayIcon(config.icon_color);
-        const mb = menubar({
-            icon,
-            width: state.width,
-            height: state.height,
-            alwaysOnTop: IS_DEBUG || !!config.always_on_top,
-            tooltip: 'Mstdn',
-            autoHideMenuBar: true,
-            useContentSize: true,
-            show: false,
-            webPreferences: {
-                nodeIntegration: false,
-                sandbox: true,
-                preload: PRELOAD_JS,
-            },
-        });
-        mb.once('ready', () => mb.showWindow());
-        mb.once('after-create-window', () => {
-            log.debug('Menubar application was launched');
-            if (config.hot_key) {
-                globalShortcut.register(config.hot_key, () => {
-                    if (mb.window.isFocused()) {
-                        log.debug('Toggle window: shown -> hidden');
-                        mb.hideWindow();
-                    } else {
-                        log.debug('Toggle window: hidden -> shown');
-                        mb.showWindow();
-                    }
-                });
-                log.debug('Hot key was set to:', config.hot_key);
-            }
-            if (IS_DEBUG) {
-                mb.window.webContents.openDevTools({mode: 'detach'});
-            }
-            mb.window.webContents.on('dom-ready', () => {
-                log.debug('Send config to renderer procress');
-                mb.window.webContents.send('mstdn:config', config);
-            });
-            state.manage(mb.window);
-
-            resolve(mb.window);
-        });
-        mb.once('after-close', () => {
-            app.quit();
-        });
-    });
-}
diff --git a/main/default_menu.ts b/main/default_menu.ts
new file mode 100644
index 0000000..6fbcbcd
--- /dev/null
+++ b/main/default_menu.ts
@@ -0,0 +1,189 @@
+import * as path from 'path';
+import {Menu, shell, app} from 'electron';
+
+export default function defaultMenu() {
+    const template: Electron.MenuItemOptions[] = [
+        {
+            label: 'Edit',
+            submenu: [
+                {
+                    label: 'Edit Config',
+                    click() {
+                        shell.openItem(path.join(app.getPath('userData'), 'config.json'));
+                    }
+                },
+                {
+                    type: 'separator'
+                },
+                {
+                    role: 'undo'
+                },
+                {
+                    role: 'redo'
+                },
+                {
+                    type: 'separator'
+                },
+                {
+                    role: 'cut'
+                },
+                {
+                    role: 'copy'
+                },
+                {
+                    role: 'paste'
+                },
+                {
+                    role: 'pasteandmatchstyle'
+                },
+                {
+                    role: 'delete'
+                },
+                {
+                    role: 'selectall'
+                }
+            ]
+        },
+        {
+            label: 'View',
+            submenu: [
+                {
+                    role: 'reload'
+                },
+                {
+                    role: 'toggledevtools'
+                },
+                {
+                    type: 'separator'
+                },
+                {
+                    role: 'resetzoom'
+                },
+                {
+                    role: 'zoomin'
+                },
+                {
+                    role: 'zoomout'
+                },
+                {
+                    type: 'separator'
+                },
+                {
+                    role: 'togglefullscreen'
+                }
+            ]
+        },
+        {
+            role: 'window',
+            submenu: [
+                {
+                    role: 'minimize'
+                },
+                {
+                    role: 'close'
+                }
+            ]
+        },
+        {
+            role: 'help',
+            submenu: [
+                {
+                    label: 'Learn More',
+                    click() {
+                        shell.openExternal('https://github.com/rhysd/Mstdn#readme');
+                    }
+                },
+                {
+                    label: 'Search Issues',
+                    click() {
+                        shell.openExternal('https://github.com/rhysd/Mstdn/issues');
+                    }
+                }
+            ]
+        }
+    ];
+
+    if (process.platform === 'darwin') {
+        template.unshift({
+            label: 'Mstdn',
+            submenu: [
+                {
+                    role: 'about'
+                },
+                {
+                    type: 'separator'
+                },
+                {
+                    role: 'services',
+                    submenu: []
+                },
+                {
+                    type: 'separator'
+                },
+                {
+                    role: 'hide'
+                },
+                {
+                    role: 'hideothers'
+                },
+                {
+                    role: 'unhide'
+                },
+                {
+                    type: 'separator'
+                },
+                {
+                    role: 'quit'
+                }
+            ]
+        });
+
+        (template[1].submenu as Electron.MenuItemOptions[]).push(
+            {
+                type: 'separator'
+            },
+            {
+                label: 'Speech',
+                submenu: [
+                    {
+                        role: 'startspeaking'
+                    },
+                    {
+                        role: 'stopspeaking'
+                    }
+                ]
+            }
+        );
+
+        template[3].submenu = [
+            {
+                role: 'close'
+            },
+            {
+                role: 'minimize'
+            },
+            {
+                role: 'zoom'
+            },
+            {
+                type: 'separator'
+            },
+            {
+                role: 'front'
+            }
+        ];
+    } else {
+        template.unshift(
+            {
+                label: 'File',
+                submenu: [
+                    {
+                    role: 'quit'
+                    }
+                ]
+            }
+        );
+    }
+
+    return Menu.buildFromTemplate(template);
+}
diff --git a/main/index.ts b/main/index.ts
index a4d5a70..f1da477 100644
--- a/main/index.ts
+++ b/main/index.ts
@@ -3,6 +3,10 @@ import log from './log';
 import startApp from './app';
 import loadConfig from './config';
 
+// default_app sets app.on('all-window-closed', () => app.quit()) before
+// loading this application. We need to disable the callback.
+app.removeAllListeners();
+
 const appReady = new Promise<void>(resolve => app.once('ready', resolve));
 
 process.on('unhandledRejection', (reason: string) => {
@@ -16,7 +20,7 @@ app.on('will-quit', () => {
 Promise.all([
     loadConfig(),
     appReady
-]).then(([config, _]) => startApp(config)).then(win => {
-    win.open();
+]).then(([config, _]) => startApp(config)).then(mstdn => {
+    mstdn.start();
     log.debug('Application launched!');
 });
diff --git a/main/window.ts b/main/window.ts
new file mode 100644
index 0000000..0e9178b
--- /dev/null
+++ b/main/window.ts
@@ -0,0 +1,236 @@
+import * as path from 'path';
+import {app, BrowserWindow, globalShortcut, Tray, shell, dialog, Menu} from 'electron';
+import windowState = require('electron-window-state');
+import * as menubar from 'menubar';
+import {Config, Account} from './config';
+import {partitionForAccount} from './account_switcher';
+import log from './log';
+
+const IS_DEBUG = process.env.NODE_ENV === 'development';
+const IS_DARWIN = process.platform === 'darwin';
+const APP_ICON = path.join(__dirname, '..', 'resources', 'icon', 'icon.png');
+const PRELOAD_JS = path.join(__dirname, '..', 'renderer', 'preload.js');
+
+export default class Window {
+    static create(account: Account, config: Config, mb: Menubar.MenubarApp | null = null) {
+        if (config.normal_window) {
+            return startNormalWindow(account, config);
+        } else {
+            return startMenuBar(account, config, mb);
+        }
+    }
+
+    constructor(
+        public browser: Electron.BrowserWindow,
+        public state: any /*XXX: ElectronWindowState.WindowState */,
+        public account: Account,
+        public menubar: Menubar.MenubarApp | null,
+    ) {
+        if (!IS_DARWIN) {
+            // Users can still access menu bar with pressing Alt key.
+            browser.setMenu(Menu.getApplicationMenu());
+        }
+
+        browser.webContents.on('will-navigate', (e, url) => {
+            if (!url.startsWith(`https://${this.account.host}`)) {
+                e.preventDefault();
+                shell.openExternal(url);
+            }
+            log.debug('Opened URL with external browser (will-navigate)', url);
+        });
+        browser.webContents.on('new-window', (e, url) => {
+            e.preventDefault();
+            shell.openExternal(url);
+            log.debug('Opened URL with external browser (new-window)', url);
+        });
+
+        browser.webContents.session.setPermissionRequestHandler((contents, permission, callback) => {
+            if (permission !== 'geolocation' && permission !== 'media') {
+                // Granted
+                log.debug('Permission was granted', permission);
+                callback(true);
+                return;
+            }
+
+            log.debug('Create dialog for user permission', permission);
+            dialog.showMessageBox({
+                type: 'question',
+                buttons: ['Accept', 'Reject'],
+                message: `Permission '${permission}' is requested by ${contents.getURL()}`,
+                detail: "Please choose one of 'Accept' or 'Reject'",
+            }, (buttonIndex: number) => {
+                const granted = buttonIndex === 0;
+                callback(granted);
+            });
+        });
+    }
+
+    open(url: string) {
+        log.debug('Open URL:', url);
+        this.browser.loadURL(url);
+    }
+
+    close() {
+        log.debug('Closing window:', this.account);
+        this.state.unmanage();
+        this.browser.webContents.removeAllListeners();
+        this.browser.removeAllListeners();
+        if (this.menubar) {
+            // Note:
+            // menubar.windowClear() won't be called because all listners was removed
+            delete this.menubar.window;
+        }
+        this.browser.close();
+    }
+}
+
+function trayIcon(color: string) {
+    return path.join(__dirname, '..', 'resources', 'icon', `tray-icon-${
+        color === 'white' ? 'white' : 'black'
+    }@2x.png`);
+}
+
+function startNormalWindow(account: Account, config: Config): Promise<Window> {
+    log.debug('Setup a normal window');
+    return new Promise<Window>(resolve => {
+        const state = windowState({
+            defaultWidth: 600,
+            defaultHeight: 800,
+        });
+        const win = new BrowserWindow({
+            width: state.width,
+            height: state.height,
+            x: state.x,
+            y: state.y,
+            icon: APP_ICON,
+            show: false,
+            useContentSize: true,
+            autoHideMenuBar: true,
+            webPreferences: {
+                nodeIntegration: false,
+                sandbox: true,
+                preload: PRELOAD_JS,
+                partition: partitionForAccount(account),
+            },
+        });
+        win.once('ready-to-show', () => {
+            win.show();
+        });
+        win.once('closed', () => {
+            app.quit();
+        });
+
+        if (state.isFullScreen) {
+            win.setFullScreen(true);
+        } else if (state.isMaximized) {
+            win.maximize();
+        }
+        state.manage(win);
+
+        const toggleWindow = () => {
+            if (win.isFocused()) {
+                log.debug('Toggle window: shown -> hidden');
+                if (IS_DARWIN) {
+                    app.hide();
+                } else {
+                    win.hide();
+                }
+            } else {
+                log.debug('Toggle window: hidden -> shown');
+                win.show();
+            }
+        };
+
+        win.webContents.on('dom-ready', () => {
+            log.debug('Send config to renderer procress');
+            win.webContents.send('mstdn:config', config, account);
+        });
+        win.webContents.once('dom-ready', () => {
+            log.debug('Normal window application was launched');
+            if (config.hot_key) {
+                globalShortcut.register(config.hot_key, toggleWindow);
+                log.debug('Hot key was set to:', config.hot_key);
+            }
+            if (IS_DEBUG) {
+                win.webContents.openDevTools({mode: 'detach'});
+            }
+        });
+
+        const normalIcon = trayIcon(config.icon_color);
+        const tray = new Tray(normalIcon);
+        tray.on('click', toggleWindow);
+        tray.on('double-click', toggleWindow);
+        if (IS_DARWIN) {
+            tray.setHighlightMode('never');
+        }
+
+        resolve(new Window(win, state, account, null));
+    });
+}
+
+function startMenuBar(account: Account, config: Config, bar: Menubar.MenubarApp | null): Promise<Window> {
+    log.debug('Setup a menubar window');
+    return new Promise<Window>(resolve => {
+        const state = windowState({
+            defaultWidth: 350,
+            defaultHeight: 420,
+        });
+        const icon = trayIcon(config.icon_color);
+        const mb = bar || menubar({
+            icon,
+            width: state.width,
+            height: state.height,
+            alwaysOnTop: IS_DEBUG || !!config.always_on_top,
+            tooltip: 'Mstdn',
+            useContentSize: true,
+            autoHideMenuBar: true,
+            show: false,
+            showDockIcon: true,
+            webPreferences: {
+                nodeIntegration: false,
+                sandbox: true,
+                preload: PRELOAD_JS,
+                partition: partitionForAccount(account),
+            },
+        });
+        mb.once('after-create-window', () => {
+            log.debug('Menubar application was launched');
+            if (config.hot_key) {
+                globalShortcut.register(config.hot_key, () => {
+                    if (mb.window.isFocused()) {
+                        log.debug('Toggle window: shown -> hidden');
+                        mb.hideWindow();
+                    } else {
+                        log.debug('Toggle window: hidden -> shown');
+                        mb.showWindow();
+                    }
+                });
+                log.debug('Hot key was set to:', config.hot_key);
+            }
+            if (IS_DEBUG) {
+                mb.window.webContents.openDevTools({mode: 'detach'});
+            }
+            mb.window.webContents.on('dom-ready', () => {
+                log.debug('Send config to renderer procress');
+                mb.window.webContents.send('mstdn:config', config, account);
+            });
+            state.manage(mb.window);
+
+            resolve(new Window(mb.window, state, account, mb));
+        });
+        mb.once('after-close', () => {
+            app.quit();
+        });
+        if (bar) {
+            log.debug('Recreate menubar window with different partition:', account);
+            const pref = mb.getOption('webPreferences');
+            pref.partition = partitionForAccount(account);
+            mb.setOption('webPreferences', pref);
+            mb.showWindow();
+        } else {
+            log.debug('New menubar instance was created:', account);
+            mb.once('ready', () => mb.showWindow());
+        }
+    });
+}
+
diff --git a/renderer/index.ts b/renderer/index.ts
index d9135a2..f78c6d2 100644
--- a/renderer/index.ts
+++ b/renderer/index.ts
@@ -1,5 +1,5 @@
 import * as Mousetrap from 'mousetrap';
-import {Config} from '../main/config';
+import {Config, Account} from '../main/config';
 import * as Ipc from './ipc';
 import log from './log';
 
@@ -39,7 +39,7 @@ function setupKeybinds(keybinds: {[key: string]: string}, host: string) {
             });
         } else {
             const func = ShortcutActions[action];
-            if (func === undefined) {
+            if (!func) {
                 log.error('Unknown shortcut action:', action);
                 continue;
             }
@@ -52,8 +52,10 @@ function setupKeybinds(keybinds: {[key: string]: string}, host: string) {
     }
 }
 
-Ipc.on('mstdn:config', (config: Config) => {
-    // TODO: Temporary. It should be fixed on supporting multi-account.
-    const host = config.accounts[0].host;
+let config: Config | null = null;
+
+Ipc.on('mstdn:config', (c: Config, a: Account) => {
+    config = c;
+    const host = a.host;
     setupKeybinds(config.keymaps, host);
 });
diff --git a/renderer/ipc.ts b/renderer/ipc.ts
index a954c5c..b5389e8 100644
--- a/renderer/ipc.ts
+++ b/renderer/ipc.ts
@@ -5,7 +5,7 @@ const ipc = electron.ipcRenderer;
 
 export function on(channel: IpcChannel, callback: (...args: any[]) => void) {
     ipc.on(channel, (...args: any[]) => {
-        log.debug('IPC: Received from:', channel, args);
+        log.info('IPC: Received from:', channel, args);
         callback(...args);
     });
 }
diff --git a/typings/ipc.d.ts b/typings/ipc.d.ts
index becc519..2312831 100644
--- a/typings/ipc.d.ts
+++ b/typings/ipc.d.ts
@@ -1,3 +1,4 @@
 type IpcChannel
     = 'mstdn:config'
+    | 'mstdn:change-account'
 ;