diff --git a/README.md b/README.md
index d66b265..8822dd0 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ To API Level 14 or later are supported
 [SimpleFloating](http://youtu.be/nb8M2p0agF4)
 
 ## Requirements
-Target Sdk Version : 25  
+Target Sdk Version : 26  
 Min Sdk Version : 14  
 
 ## How to use
@@ -69,6 +69,7 @@ Describe the process (`onFinishFloatingView`) that is called when you exit the F
 ```  
   
 6) Define the Service to AndroidManifest
+
 example)
 ```java
     <application ...>
@@ -81,10 +82,26 @@ example)
     </application>
 ```
   
-7) Describe the process to start the Service (example of Fragment)
+7) Describe the process to start the Service (run on foreground)
 ```java
-    final Activity activity = getActivity();
-    activity.startService(new Intent(activity, ChatHeadService.class));
+    final Intent intent = new Intent(activity, ChatHeadService.class);
+    ContextCompat.startForegroundService(activity, intent);
+```
+
+8) Create notification channel (targetSdkVersion >= 26)
+
+example)
+```java
+if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+    final String channelId = getString(R.string.default_floatingview_channel_id);
+    final String channelName = getString(R.string.default_floatingview_channel_name);
+    final NotificationChannel defaultChannel = new NotificationChannel(channelId, channelName, NotificationManager.IMPORTANCE_MIN);
+    final NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
+    if (manager != null) {
+        manager.createNotificationChannel(defaultChannel);
+    }
+}
+
 ```
 
 ## Static Options
diff --git a/build.gradle b/build.gradle
index bdd76f4..38f9ac3 100644
--- a/build.gradle
+++ b/build.gradle
@@ -3,9 +3,10 @@
 buildscript {
     repositories {
         jcenter()
+        google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.3.3'
+        classpath 'com.android.tools.build:gradle:3.0.0'
         classpath 'com.github.dcendents:android-maven-gradle-plugin:1.3'
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
@@ -16,12 +17,13 @@ allprojects {
     repositories {
         maven { url "https://jitpack.io" }
         jcenter()
+        google()
     }
 }
 
 ext {
-    compileSdkVersion = 25
-    buildToolsVersion = '25.0.2'
-    targetSdkVersion = 25
+    compileSdkVersion = 26
+    buildToolsVersion = '26.0.2'
+    targetSdkVersion = 26
     minSdkVersion = 14
 }
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index d71758f..50da505 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
-#Mon Jun 26 10:48:16 JST 2017
+#Wed Sep 13 12:18:11 JST 2017
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip
diff --git a/library/build.gradle b/library/build.gradle
index 478d397..7471069 100644
--- a/library/build.gradle
+++ b/library/build.gradle
@@ -13,8 +13,8 @@ android {
 }
 
 dependencies {
-    compile 'com.android.support:support-annotations:25.3.1'
-    compile 'com.android.support:support-compat:25.3.1'
+    compile 'com.android.support:support-annotations:26.1.0'
+    compile 'com.android.support:support-compat:26.1.0'
 }
 
 // build a jar with source files
diff --git a/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/FloatingView.java b/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/FloatingView.java
index 7b34dff..a071fba 100644
--- a/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/FloatingView.java
+++ b/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/FloatingView.java
@@ -127,6 +127,11 @@ class FloatingView extends FrameLayout implements ViewTreeObserver.OnPreDrawList
      */
     static final int DEFAULT_HEIGHT = ViewGroup.LayoutParams.WRAP_CONTENT;
 
+    /**
+     * Overlay Type
+     */
+    private static final int OVERLAY_TYPE;
+
     /**
      * WindowManager
      */
@@ -297,6 +302,14 @@ class FloatingView extends FrameLayout implements ViewTreeObserver.OnPreDrawList
      */
     private int mRotation;
 
+    static {
+        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.N_MR1) {
+            OVERLAY_TYPE = WindowManager.LayoutParams.TYPE_PRIORITY_PHONE;
+        } else {
+            OVERLAY_TYPE = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
+        }
+    }
+
     /**
      * コンストラクタ
      *
@@ -310,7 +323,7 @@ class FloatingView extends FrameLayout implements ViewTreeObserver.OnPreDrawList
         mWindowManager.getDefaultDisplay().getMetrics(mMetrics);
         mParams.width = ViewGroup.LayoutParams.WRAP_CONTENT;
         mParams.height = ViewGroup.LayoutParams.WRAP_CONTENT;
-        mParams.type = WindowManager.LayoutParams.TYPE_PRIORITY_PHONE;
+        mParams.type = OVERLAY_TYPE;
         mParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE |
                 WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS |
                 WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;
diff --git a/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/FullscreenObserverView.java b/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/FullscreenObserverView.java
index bf7516d..4b77351 100644
--- a/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/FullscreenObserverView.java
+++ b/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/FullscreenObserverView.java
@@ -36,6 +36,11 @@ class FullscreenObserverView extends View implements ViewTreeObserver.OnGlobalLa
      */
     static final int NO_LAST_VISIBILITY = -1;
 
+    /**
+     * Overlay Type
+     */
+    private static final int OVERLAY_TYPE;
+
     /**
      * WindowManager.LayoutParams
      */
@@ -57,6 +62,13 @@ class FullscreenObserverView extends View implements ViewTreeObserver.OnGlobalLa
      */
     private final Rect mWindowRect;
 
+    static {
+        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.N_MR1) {
+            OVERLAY_TYPE = WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY;
+        } else {
+            OVERLAY_TYPE = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
+        }
+    }
 
     /**
      * コンストラクタ
@@ -71,7 +83,7 @@ class FullscreenObserverView extends View implements ViewTreeObserver.OnGlobalLa
         mParams = new WindowManager.LayoutParams();
         mParams.width = 1;
         mParams.height = ViewGroup.LayoutParams.MATCH_PARENT;
-        mParams.type = WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY;
+        mParams.type = OVERLAY_TYPE;
         mParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE |
                 WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE |
                 WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;
diff --git a/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/TrashView.java b/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/TrashView.java
index 3588c56..8ca2db0 100644
--- a/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/TrashView.java
+++ b/library/src/main/java/jp/co/recruit_lifestyle/android/floatingview/TrashView.java
@@ -100,6 +100,11 @@ class TrashView extends FrameLayout implements ViewTreeObserver.OnPreDrawListene
      */
     private static final int LONG_PRESS_TIMEOUT = ViewConfiguration.getLongPressTimeout();
 
+    /**
+     * Overlay Type
+     */
+    private static final int OVERLAY_TYPE;
+
     /**
      * WindowManager
      */
@@ -180,6 +185,14 @@ class TrashView extends FrameLayout implements ViewTreeObserver.OnPreDrawListene
      */
     private boolean mIsEnabled;
 
+    static {
+        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.N_MR1) {
+            OVERLAY_TYPE = WindowManager.LayoutParams.TYPE_PRIORITY_PHONE;
+        } else {
+            OVERLAY_TYPE = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
+        }
+    }
+
     /**
      * コンストラクタ
      *
@@ -196,7 +209,7 @@ class TrashView extends FrameLayout implements ViewTreeObserver.OnPreDrawListene
         mParams = new WindowManager.LayoutParams();
         mParams.width = ViewGroup.LayoutParams.MATCH_PARENT;
         mParams.height = ViewGroup.LayoutParams.MATCH_PARENT;
-        mParams.type = WindowManager.LayoutParams.TYPE_PRIORITY_PHONE;
+        mParams.type = OVERLAY_TYPE;
         mParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE |
                 WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE |
                 WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;
diff --git a/sample/build.gradle b/sample/build.gradle
index 63d36a5..7081ee0 100644
--- a/sample/build.gradle
+++ b/sample/build.gradle
@@ -21,7 +21,6 @@ android {
 
 dependencies {
     compile fileTree(dir: 'libs', include: ['*.jar'])
-    compile 'com.android.support:support-v13:25.3.1'
-    compile 'com.android.support:preference-v14:25.3.1'
+    compile 'com.android.support:preference-v14:26.1.0'
     compile project(':library')
 }
diff --git a/sample/src/main/java/jp/co/recruit_lifestyle/sample/MainActivity.java b/sample/src/main/java/jp/co/recruit_lifestyle/sample/MainActivity.java
index 231680f..659dec9 100644
--- a/sample/src/main/java/jp/co/recruit_lifestyle/sample/MainActivity.java
+++ b/sample/src/main/java/jp/co/recruit_lifestyle/sample/MainActivity.java
@@ -2,6 +2,9 @@
 
 import android.app.Activity;
 import android.app.FragmentTransaction;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.os.Build;
 import android.os.Bundle;
 
 import jp.co.recruit.floatingview.R;
@@ -15,6 +18,17 @@ protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
+        // create default notification channel
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            final String channelId = getString(R.string.default_floatingview_channel_id);
+            final String channelName = getString(R.string.default_floatingview_channel_name);
+            final NotificationChannel defaultChannel = new NotificationChannel(channelId, channelName, NotificationManager.IMPORTANCE_MIN);
+            final NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
+            if (manager != null) {
+                manager.createNotificationChannel(defaultChannel);
+            }
+        }
+
         if (savedInstanceState == null) {
             FragmentTransaction ft = getFragmentManager().beginTransaction();
             ft.add(R.id.container, FloatingViewControlFragment.newInstance());
diff --git a/sample/src/main/java/jp/co/recruit_lifestyle/sample/fragment/FloatingViewControlFragment.java b/sample/src/main/java/jp/co/recruit_lifestyle/sample/fragment/FloatingViewControlFragment.java
index af8cb36..58677e7 100644
--- a/sample/src/main/java/jp/co/recruit_lifestyle/sample/fragment/FloatingViewControlFragment.java
+++ b/sample/src/main/java/jp/co/recruit_lifestyle/sample/fragment/FloatingViewControlFragment.java
@@ -10,6 +10,7 @@
 import android.os.Build;
 import android.os.Bundle;
 import android.provider.Settings;
+import android.support.v4.content.ContextCompat;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -111,13 +112,15 @@ public void onActivityResult(int requestCode, int resultCode, Intent data) {
     private void showChatHead(Context context, boolean isShowOverlayPermission) {
         // API22以下かチェック
         if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.LOLLIPOP_MR1) {
-            context.startService(new Intent(context, ChatHeadService.class));
+            final Intent intent = new Intent(context, ChatHeadService.class);
+            ContextCompat.startForegroundService(context, intent);
             return;
         }
 
         // 他のアプリの上に表示できるかチェック
         if (Settings.canDrawOverlays(context)) {
-            context.startService(new Intent(context, ChatHeadService.class));
+            final Intent intent = new Intent(context, ChatHeadService.class);
+            ContextCompat.startForegroundService(context, intent);
             return;
         }
 
@@ -138,13 +141,15 @@ private void showChatHead(Context context, boolean isShowOverlayPermission) {
     private void showCustomFloatingView(Context context, boolean isShowOverlayPermission) {
         // API22以下かチェック
         if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.LOLLIPOP_MR1) {
-            context.startService(new Intent(context, CustomFloatingViewService.class));
+            final Intent intent = new Intent(context, CustomFloatingViewService.class);
+            ContextCompat.startForegroundService(context, intent);
             return;
         }
 
         // 他のアプリの上に表示できるかチェック
         if (Settings.canDrawOverlays(context)) {
-            context.startService(new Intent(context, CustomFloatingViewService.class));
+            final Intent intent = new Intent(context, CustomFloatingViewService.class);
+            ContextCompat.startForegroundService(context, intent);
             return;
         }
 
diff --git a/sample/src/main/java/jp/co/recruit_lifestyle/sample/service/ChatHeadService.java b/sample/src/main/java/jp/co/recruit_lifestyle/sample/service/ChatHeadService.java
index fc3910d..d11cd2a 100644
--- a/sample/src/main/java/jp/co/recruit_lifestyle/sample/service/ChatHeadService.java
+++ b/sample/src/main/java/jp/co/recruit_lifestyle/sample/service/ChatHeadService.java
@@ -68,7 +68,7 @@ public void onClick(View v) {
         mFloatingViewManager.addViewToWindow(iconView, options);
 
         // 常駐起動
-        startForeground(NOTIFICATION_ID, createNotification());
+        startForeground(NOTIFICATION_ID, createNotification(this));
 
         return START_REDELIVER_INTENT;
     }
@@ -125,12 +125,12 @@ private void destroy() {
      * 通知を表示します。
      * クリック時のアクションはありません。
      */
-    private Notification createNotification() {
-        final NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
+    private static Notification createNotification(Context context) {
+        final NotificationCompat.Builder builder = new NotificationCompat.Builder(context, context.getString(R.string.default_floatingview_channel_id));
         builder.setWhen(System.currentTimeMillis());
         builder.setSmallIcon(R.mipmap.ic_launcher);
-        builder.setContentTitle(getString(R.string.chathead_content_title));
-        builder.setContentText(getString(R.string.content_text));
+        builder.setContentTitle(context.getString(R.string.chathead_content_title));
+        builder.setContentText(context.getString(R.string.content_text));
         builder.setOngoing(true);
         builder.setPriority(NotificationCompat.PRIORITY_MIN);
         builder.setCategory(NotificationCompat.CATEGORY_SERVICE);
diff --git a/sample/src/main/java/jp/co/recruit_lifestyle/sample/service/CustomFloatingViewService.java b/sample/src/main/java/jp/co/recruit_lifestyle/sample/service/CustomFloatingViewService.java
index 734689c..cebc2fd 100644
--- a/sample/src/main/java/jp/co/recruit_lifestyle/sample/service/CustomFloatingViewService.java
+++ b/sample/src/main/java/jp/co/recruit_lifestyle/sample/service/CustomFloatingViewService.java
@@ -13,7 +13,6 @@
 import android.support.v4.app.NotificationCompat;
 import android.text.TextUtils;
 import android.util.DisplayMetrics;
-import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.WindowManager;
@@ -87,7 +86,7 @@ public void onClick(View v) {
         mFloatingViewManager.addViewToWindow(iconView, options);
 
         // 常駐起動
-        startForeground(NOTIFICATION_ID, createNotification());
+        startForeground(NOTIFICATION_ID, createNotification(this));
 
         return START_REDELIVER_INTENT;
     }
@@ -145,19 +144,19 @@ private void destroy() {
     /**
      * 通知を表示します。
      */
-    private Notification createNotification() {
-        final NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
+    private static Notification createNotification(Context context) {
+        final NotificationCompat.Builder builder = new NotificationCompat.Builder(context, context.getString(R.string.default_floatingview_channel_id));
         builder.setWhen(System.currentTimeMillis());
         builder.setSmallIcon(R.mipmap.ic_launcher);
-        builder.setContentTitle(getString(R.string.mail_content_title));
-        builder.setContentText(getString(R.string.content_text));
+        builder.setContentTitle(context.getString(R.string.mail_content_title));
+        builder.setContentText(context.getString(R.string.content_text));
         builder.setOngoing(true);
         builder.setPriority(NotificationCompat.PRIORITY_MIN);
         builder.setCategory(NotificationCompat.CATEGORY_SERVICE);
 
         // PendingIntent作成
-        final Intent notifyIntent = new Intent(this, DeleteActionActivity.class);
-        PendingIntent notifyPendingIntent = PendingIntent.getActivity(this, 0, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);
+        final Intent notifyIntent = new Intent(context, DeleteActionActivity.class);
+        PendingIntent notifyPendingIntent = PendingIntent.getActivity(context, 0, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);
         builder.setContentIntent(notifyPendingIntent);
 
         return builder.build();
diff --git a/sample/src/main/res/values/strings.xml b/sample/src/main/res/values/strings.xml
index 45cac86..937a0b1 100644
--- a/sample/src/main/res/values/strings.xml
+++ b/sample/src/main/res/values/strings.xml
@@ -16,4 +16,6 @@
     <string name="touch_finished_position" formatted="false">Current position (%d,%d)</string>
     <string name="deleted_soon">FloatingView will be deleted soon.</string>
     <string name="finish_deleted">FloatingView has been deleted.</string>
+    <string name="default_floatingview_channel_id">default_floatingview_channel</string>
+    <string name="default_floatingview_channel_name">Default Channel</string>
 </resources>