diff --git a/Suohai/SuohaiController.swift b/Suohai/SuohaiController.swift
index a19e782..d3da816 100644
--- a/Suohai/SuohaiController.swift
+++ b/Suohai/SuohaiController.swift
@@ -16,7 +16,7 @@ class SuohaiController: NSObject {
 
     override init() {
         super.init()
-        self.setupItems()
+        self.prepareItems()
         NotificationCenter.addObserver(observer: self, selector: #selector(reloadMenu), name: .audioDevicesDidChange)
     }
 
@@ -24,22 +24,9 @@ class SuohaiController: NSObject {
         NotificationCenter.removeObserver(observer: self, name: .audioDevicesDidChange)
     }
 
-    private func setupItems() {
-        self.menu = {
-            let menu = NSMenu()
-            menu.delegate = self
-            return menu
-        }()
-        self.statusItem = {
-            let item = NSStatusBar.system.statusItem(withLength: NSStatusItem.variableLength)
-            item.image = #imageLiteral(resourceName: "StatusItem")
-            item.target = self
-            item.menu = self.menu
-            return item
-        }()
-    }
-
-    @objc func reloadMenu() {
+    // Mark: Notification handler
+    @objc
+    func reloadMenu() {
         let listener = SuohaiListener.shared
         self.menu.removeAllItems()
         self.menu.addItem(NSMenuItem(title: NSLocalizedString("OutputDevices", comment: "")))
@@ -73,7 +60,8 @@ class SuohaiController: NSObject {
     }
 
     // MARK: Event method
-    @objc private func selectOutputDeviceAction(_ sender: NSMenuItem) {
+    @objc
+    private func selectOutputDeviceAction(_ sender: NSMenuItem) {
         let listener = SuohaiListener.shared
         guard let device = listener.devices.first(where: {$0.id == UInt32(sender.tag)}) else {
             return
@@ -81,7 +69,8 @@ class SuohaiController: NSObject {
         listener.selectedOutputDeviceID = listener.selectedOutputDeviceID != device.id ? device.id : nil
     }
 
-    @objc private func selectInputDeviceAction(_ sender: NSMenuItem) {
+    @objc
+    private func selectInputDeviceAction(_ sender: NSMenuItem) {
         let listener = SuohaiListener.shared
         guard let device = listener.devices.first(where: {$0.id == UInt32(sender.tag)}) else {
             return
@@ -89,9 +78,26 @@ class SuohaiController: NSObject {
         listener.selectedInputDeviceID = listener.selectedInputDeviceID != device.id ? device.id : nil
     }
 
-    @objc private func quitAction(_ sender: NSMenuItem) {
+    @objc
+    private func quitAction(_ sender: NSMenuItem) {
         NSApplication.shared.terminate(nil)
     }
+
+    // MARK: UI method
+    private func prepareItems() {
+        self.menu = {
+            let menu = NSMenu()
+            menu.delegate = self
+            return menu
+        }()
+        self.statusItem = {
+            let item = NSStatusBar.system.statusItem(withLength: NSStatusItem.variableLength)
+            item.image = #imageLiteral(resourceName: "StatusItem")
+            item.target = self
+            item.menu = self.menu
+            return item
+        }()
+    }
 }
 
 extension SuohaiController: NSMenuDelegate {
diff --git a/Suohai/SuohaiListener.swift b/Suohai/SuohaiListener.swift
index 7a22ed1..a5d294c 100644
--- a/Suohai/SuohaiListener.swift
+++ b/Suohai/SuohaiListener.swift
@@ -24,6 +24,11 @@ enum SuohaiNotification: String {
     }
 }
 
+struct SuohaiDefaultKeys {
+    static let audioInputDeviceID = "AudioInputDeviceID"
+    static let audioOutputDeviceID = "AudioOutputDeviceID"
+}
+
 enum AudioDeviceType {
     case output
     case input
@@ -54,17 +59,17 @@ struct AudioAddress {
 }
 
 struct AudioListener {
-    static var devices: AudioObjectPropertyListenerProc = {_, _, _, _ in
+    static var devices: AudioObjectPropertyListenerProc = { _, _, _, _ in
         NotificationCenter.post(suohaiNotification: .audioDevicesDidChange)
         return 0
     }
 
-    static var output: AudioObjectPropertyListenerProc = {_, _, _, _ in
+    static var output: AudioObjectPropertyListenerProc = { _, _, _, _ in
         NotificationCenter.post(suohaiNotification: .audioOutputDeviceDidChange)
         return 0
     }
 
-    static var input: AudioObjectPropertyListenerProc = {_, _, _, _ in
+    static var input: AudioObjectPropertyListenerProc = { _, _, _, _ in
         NotificationCenter.post(suohaiNotification: .audioInputDeviceDidChange)
         return 0
     }
@@ -123,23 +128,26 @@ class SuohaiListener {
 
     var selectedOutputDeviceID: AudioDeviceID? {
         didSet {
-            guard var deviceID = self.selectedOutputDeviceID else {
-                return
+            if var deviceID = self.selectedOutputDeviceID {
+                self.setOutputDevice(id: &deviceID)
             }
-            self.setOutputDevice(id: &deviceID)
+            UserDefaults.standard.set(self.selectedOutputDeviceID, forKey: SuohaiDefaultKeys.audioOutputDeviceID)
         }
     }
+
     var selectedInputDeviceID: AudioDeviceID? {
         didSet {
-            guard var deviceID = self.selectedInputDeviceID else {
-                return
+            if var deviceID = self.selectedInputDeviceID {
+                self.setInputDevice(id: &deviceID)
             }
-            self.setInputDevice(id: &deviceID)
+            UserDefaults.standard.set(self.selectedInputDeviceID, forKey: SuohaiDefaultKeys.audioInputDeviceID)
         }
     }
 
     // MARK: Lifecycle
     init() {
+        self.selectedOutputDeviceID = UserDefaults.standard.value(forKey: SuohaiDefaultKeys.audioOutputDeviceID) as? AudioDeviceID
+        self.selectedInputDeviceID = UserDefaults.standard.value(forKey: SuohaiDefaultKeys.audioInputDeviceID) as? AudioDeviceID
         NotificationCenter.addObserver(observer: self, selector: #selector(handleNotification(_:)), name: .audioDevicesDidChange)
         NotificationCenter.addObserver(observer: self, selector: #selector(handleNotification(_:)), name: .audioOutputDeviceDidChange)
         NotificationCenter.addObserver(observer: self, selector: #selector(handleNotification(_:)), name: .audioInputDeviceDidChange)
@@ -164,8 +172,19 @@ class SuohaiListener {
         AudioObjectRemovePropertyListener(AudioObjectID(kAudioObjectSystemObject), &AudioAddress.inputDevice, AudioListener.input, nil)
     }
 
+    // MARK: Private method
+    private func setOutputDevice(id: inout AudioDeviceID) {
+        AudioObjectSetPropertyData(AudioObjectID(kAudioObjectSystemObject), &AudioAddress.outputDevice, 0, nil, UInt32(MemoryLayout<AudioDeviceID>.size), &id)
+    }
+
+    private func setInputDevice(id: inout AudioDeviceID) {
+        AudioObjectSetPropertyData(AudioObjectID(kAudioObjectSystemObject), &AudioAddress.inputDevice, 0, nil, UInt32(MemoryLayout<AudioDeviceID>.size), &id)
+        UserDefaults.standard.set(id, forKey: SuohaiDefaultKeys.audioInputDeviceID)
+    }
+
     // MARK: Notification handler
-    @objc private func handleNotification(_ notification: Notification) {
+    @objc
+    private func handleNotification(_ notification: Notification) {
         if notification.name == SuohaiNotification.audioDevicesDidChange.notificationName {
             if !self.devices.contains(where: {$0.id == self.selectedOutputDeviceID}) {
                 self.selectedOutputDeviceID = nil
@@ -185,12 +204,4 @@ class SuohaiListener {
             self.setInputDevice(id: &deviceID)
         }
     }
-
-    private func setOutputDevice(id: inout AudioDeviceID) {
-        AudioObjectSetPropertyData(AudioObjectID(kAudioObjectSystemObject), &AudioAddress.outputDevice, 0, nil, UInt32(MemoryLayout<AudioDeviceID>.size), &id)
-    }
-
-    private func setInputDevice(id: inout AudioDeviceID) {
-        AudioObjectSetPropertyData(AudioObjectID(kAudioObjectSystemObject), &AudioAddress.inputDevice, 0, nil, UInt32(MemoryLayout<AudioDeviceID>.size), &id)
-    }
 }