diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index a01e6e5..c039a6e 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -22,7 +22,8 @@
         android:label="@string/app_name"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-        <activity android:name=".ui.LaunchActivity" android:theme="@style/Theme.AppCompat.NoActionBar">
+        <activity android:name=".ui.LaunchActivity" android:theme="@style/Theme.AppCompat.NoActionBar"
+            android:screenOrientation="portrait">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
@@ -31,22 +32,26 @@
         </activity>
         <activity
             android:name=".ui.edit.NoteEditActivity"
+            android:screenOrientation="portrait"
             android:label="@string/edit" />
         <activity
             android:name=".ui.NotePreviewActivity"
+            android:screenOrientation="portrait"
             android:label="@string/preview" />
         <activity
             android:name=".ui.MainActivity"
+            android:screenOrientation="portrait"
             android:label="@string/app_name" />
-        <activity android:name=".ui.SignInActivity" />
+        <activity android:name=".ui.SignInActivity" android:screenOrientation="portrait" />
         <activity
             android:name=".ui.SettingsActivity"
-            android:label="@string/settings" />
+            android:screenOrientation="portrait" android:label="@string/settings" />
         <activity
             android:name=".ui.AboutActivity"
+            android:screenOrientation="portrait"
             android:label="@string/about" />
         <activity
-            android:name=".ui.PictureViewerActivity" />
+            android:name=".ui.PictureViewerActivity" android:screenOrientation="portrait" />
 
         <service
             android:name=".background.NoteSyncService"
@@ -54,7 +59,7 @@
             android:exported="false"
             android:label="NoteSyncService" />
 
-        <activity android:name=".ui.SearchActivity" />
+        <activity android:name=".ui.SearchActivity" android:screenOrientation="portrait" />
 
         <activity
             android:name="com.tencent.bugly.beta.ui.BetaActivity"
diff --git a/app/src/main/java/org/houxg/leamonax/ui/BaseActivity.java b/app/src/main/java/org/houxg/leamonax/ui/BaseActivity.java
index 7f1e067..4bf4e9e 100644
--- a/app/src/main/java/org/houxg/leamonax/ui/BaseActivity.java
+++ b/app/src/main/java/org/houxg/leamonax/ui/BaseActivity.java
@@ -1,6 +1,5 @@
 package org.houxg.leamonax.ui;
 
-import android.content.pm.ActivityInfo;
 import android.os.Build;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
@@ -17,7 +16,6 @@ public class BaseActivity extends AppCompatActivity {
     @Override
     protected void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
             getWindow().setStatusBarColor(getResources().getColor(R.color.toolbar));
         }
diff --git a/app/src/main/java/org/houxg/leamonax/ui/NotePreviewActivity.java b/app/src/main/java/org/houxg/leamonax/ui/NotePreviewActivity.java
index 09713d6..673d083 100644
--- a/app/src/main/java/org/houxg/leamonax/ui/NotePreviewActivity.java
+++ b/app/src/main/java/org/houxg/leamonax/ui/NotePreviewActivity.java
@@ -2,6 +2,7 @@ package org.houxg.leamonax.ui;
 
 import android.content.Context;
 import android.content.Intent;
+import android.content.pm.ActivityInfo;
 import android.net.Uri;
 import android.os.Bundle;
 import android.support.v7.widget.Toolbar;
@@ -35,6 +36,8 @@ import rx.functions.Action0;
 import rx.functions.Action1;
 import rx.schedulers.Schedulers;
 
+import static android.content.res.Configuration.ORIENTATION_PORTRAIT;
+
 public class NotePreviewActivity extends BaseActivity implements EditorFragment.EditorFragmentListener {
 
     private static final String TAG = "NotePreviewActivity:";
@@ -84,6 +87,13 @@ public class NotePreviewActivity extends BaseActivity implements EditorFragment.
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
+            case R.id.action_rotate:
+                if (ORIENTATION_PORTRAIT == getResources().getConfiguration().orientation) {
+                    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
+                } else {
+                    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
+                }
+                return true;
             case R.id.action_edit:
                 startActivityForResult(NoteEditActivity.getOpenIntent(this, mNote.getId(), false), REQ_EDIT);
                 return true;
diff --git a/app/src/main/res/menu/preview.xml b/app/src/main/res/menu/preview.xml
index a49bede..93c908c 100644
--- a/app/src/main/res/menu/preview.xml
+++ b/app/src/main/res/menu/preview.xml
@@ -2,6 +2,11 @@
 <menu xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto">
 
+    <item
+        android:id="@+id/action_rotate"
+        app:showAsAction="always"
+        android:title="@string/rotate"/>
+
     <item
         android:id="@+id/action_edit"
         app:showAsAction="always"
diff --git a/app/src/main/res/values-zh/strings.xml b/app/src/main/res/values-zh/strings.xml
index 6d23acf..2853212 100644
--- a/app/src/main/res/values-zh/strings.xml
+++ b/app/src/main/res/values-zh/strings.xml
@@ -24,6 +24,7 @@
     <string name="delete_note">删除笔记</string>
     <string name="delete_note_failed">删除笔记失败</string>
     <string name="edit">编辑</string>
+    <string name="rotate">旋转</string>
     <string name="editor">编辑器</string>
     <string name="email">邮箱</string>
     <string name="email_or_password_incorrect">邮箱或密码错误</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 8e1faa0..a9e3678 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -8,6 +8,7 @@
     <string name="revert">Revert</string>
     <string name="reverting">Reverting</string>
     <string name="edit">Edit</string>
+    <string name="rotate">Rotate</string>
     <string name="link">Link</string>
     <string name="confirm">Confirm</string>
     <string name="cancel">Cancel</string>