diff --git a/app/src/androidTest/java/xyz/quaver/pupil/ExampleInstrumentedTest.kt b/app/src/androidTest/java/xyz/quaver/pupil/ExampleInstrumentedTest.kt
index 41211cc7..5a6f14f7 100644
--- a/app/src/androidTest/java/xyz/quaver/pupil/ExampleInstrumentedTest.kt
+++ b/app/src/androidTest/java/xyz/quaver/pupil/ExampleInstrumentedTest.kt
@@ -41,5 +41,6 @@ class ExampleInstrumentedTest {
 
     @Test
     fun test_doSearch() {
+
     }
 }
diff --git a/app/src/main/java/xyz/quaver/pupil/GalleryActivity.kt b/app/src/main/java/xyz/quaver/pupil/GalleryActivity.kt
index 00cbf6e8..24fe0795 100644
--- a/app/src/main/java/xyz/quaver/pupil/GalleryActivity.kt
+++ b/app/src/main/java/xyz/quaver/pupil/GalleryActivity.kt
@@ -56,6 +56,18 @@ class GalleryActivity : AppCompatActivity() {
         loadImages()
     }
 
+    override fun onResume() {
+        val preferences = android.preference.PreferenceManager.getDefaultSharedPreferences(this)
+
+        if (preferences.getBoolean("security_mode", false))
+            window.setFlags(
+                WindowManager.LayoutParams.FLAG_SECURE,
+                WindowManager.LayoutParams.FLAG_SECURE)
+        else
+            window.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        super.onResume()
+    }
+
     override fun onDestroy() {
         super.onDestroy()
         loadJob?.cancel()
diff --git a/app/src/main/java/xyz/quaver/pupil/MainActivity.kt b/app/src/main/java/xyz/quaver/pupil/MainActivity.kt
index 1b48419e..65ea4cec 100644
--- a/app/src/main/java/xyz/quaver/pupil/MainActivity.kt
+++ b/app/src/main/java/xyz/quaver/pupil/MainActivity.kt
@@ -67,10 +67,6 @@ class MainActivity : AppCompatActivity() {
         Histories.default = Histories(File(cacheDir, "histories.json"))
         super.onCreate(savedInstanceState)
 
-        window.setFlags(
-            WindowManager.LayoutParams.FLAG_SECURE,
-            WindowManager.LayoutParams.FLAG_SECURE)
-
         setContentView(R.layout.activity_main)
 
         checkPermission()
@@ -132,6 +128,18 @@ class MainActivity : AppCompatActivity() {
             super.onBackPressed()
     }
 
+    override fun onResume() {
+        val preferences = PreferenceManager.getDefaultSharedPreferences(this)
+
+        if (preferences.getBoolean("security_mode", false))
+            window.setFlags(
+                WindowManager.LayoutParams.FLAG_SECURE,
+                WindowManager.LayoutParams.FLAG_SECURE)
+        else
+            window.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        super.onResume()
+    }
+
     private fun checkPermission() {
         val permissions = arrayOf(
             Manifest.permission.WRITE_EXTERNAL_STORAGE
diff --git a/app/src/main/java/xyz/quaver/pupil/SettingsActivity.kt b/app/src/main/java/xyz/quaver/pupil/SettingsActivity.kt
index b9d95dda..d5c301ce 100644
--- a/app/src/main/java/xyz/quaver/pupil/SettingsActivity.kt
+++ b/app/src/main/java/xyz/quaver/pupil/SettingsActivity.kt
@@ -1,6 +1,7 @@
 package xyz.quaver.pupil
 
 import android.os.Bundle
+import android.preference.PreferenceManager
 import android.view.MenuItem
 import android.view.WindowManager
 import androidx.appcompat.app.AlertDialog
@@ -27,6 +28,18 @@ class SettingsActivity : AppCompatActivity() {
         supportActionBar?.setDisplayHomeAsUpEnabled(true)
     }
 
+    override fun onResume() {
+        val preferences = PreferenceManager.getDefaultSharedPreferences(this)
+
+        if (preferences.getBoolean("security_mode", false))
+            window.setFlags(
+                WindowManager.LayoutParams.FLAG_SECURE,
+                WindowManager.LayoutParams.FLAG_SECURE)
+        else
+            window.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        super.onResume()
+    }
+
     class SettingsFragment : PreferenceFragmentCompat() {
 
         private val suffix = listOf(
diff --git a/app/src/main/res/values-ja/strings.xml b/app/src/main/res/values-ja/strings.xml
index f79d7c26..b102b437 100644
--- a/app/src/main/res/values-ja/strings.xml
+++ b/app/src/main/res/values-ja/strings.xml
@@ -18,7 +18,7 @@
     <string name="update_notification_description">アップデートダウンロード中</string>
     <string name="update_title">新しいアップデートがあります</string>
     <string name="warning">注意</string>
-    <string name="settings_image_loading_title">イメージロード</string>
+    <string name="settings_miscellaneous_title">その他</string>
     <string name="settings_use_hiyobi_summary">ロード速度を向上させるためhiyobi.meからイメージロード</string>
     <string name="settings_use_hiyobi_title">hiyobi.meからロード</string>
     <string name="settings_clear_history">履歴の削除</string>
@@ -28,4 +28,6 @@
     <string name="main_drawer_home">トップ</string>
     <string name="update_download_started">ダウンロード中</string>
     <string name="update_release_note"># リリースノート(v%1$s)\n%2$s</string>
+    <string name="settings_security_mode_title">セキュリティーモード</string>
+    <string name="settings_security_mode_summary">アプリ履歴でアプリの画面を表示しない</string>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values-ko/strings.xml b/app/src/main/res/values-ko/strings.xml
index 309a4a2d..95f970f6 100644
--- a/app/src/main/res/values-ko/strings.xml
+++ b/app/src/main/res/values-ko/strings.xml
@@ -18,7 +18,7 @@
     <string name="main_no_result">결과 없음</string>
     <string name="main_search">검색</string>
     <string name="settings_cache_title">캐시</string>
-    <string name="settings_image_loading_title">이미지 로딩</string>
+    <string name="settings_miscellaneous_title">기타</string>
     <string name="settings_use_hiyobi_summary">속도 향상을 위해 가능하면 hiyobi.me에서 이미지 로드</string>
     <string name="settings_use_hiyobi_title">hiyobi.me 사용</string>
     <string name="settings_clear_history">히스토리 삭제</string>
@@ -28,4 +28,6 @@
     <string name="main_drawer_home">홈</string>
     <string name="update_download_started">다운로드 중</string>
     <string name="update_release_note"># 릴리즈 노트(v%1$s)\n%2$s</string>
+    <string name="settings_security_mode_summary">최근 앱 목록 창에서 앱 화면을 보이지 않게 합니다</string>
+    <string name="settings_security_mode_title">보안 모드 활성화</string>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 3fc93060..ac81600a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -43,8 +43,10 @@
     <string name="settings_clear_history">Clear history</string>
     <string name="settings_clear_history_alert_message">Do you want to clear histories?</string>
     <string name="settings_clear_history_summary">%1$d histories saved</string>
-    <string name="settings_image_loading_title">Image Loading</string>
+    <string name="settings_miscellaneous_title">Miscellaneous</string>
     <string name="settings_use_hiyobi_title">Use hiyobi.me</string>
     <string name="settings_use_hiyobi_summary">Load images from hiyobi.me to improve loading speed (if available)</string>
+    <string name="settings_security_mode_title">Enable security mode</string>
+    <string name="settings_security_mode_summary">Enable security mode to make the screen invisible on recent app window</string>
 
 </resources>
diff --git a/app/src/main/res/xml/root_preferences.xml b/app/src/main/res/xml/root_preferences.xml
index 5dbfcadf..9ad7233a 100644
--- a/app/src/main/res/xml/root_preferences.xml
+++ b/app/src/main/res/xml/root_preferences.xml
@@ -35,13 +35,19 @@
     </PreferenceCategory>
 
     <PreferenceCategory
-        app:title="@string/settings_image_loading_title">
+        app:title="@string/settings_miscellaneous_title">
 
         <SwitchPreference
             app:key="use_hiyobi"
             app:title="@string/settings_use_hiyobi_title"
             app:summary="@string/settings_use_hiyobi_summary"/>
 
+        <SwitchPreference
+            app:key="security_mode"
+            app:title="@string/settings_security_mode_title"
+            app:summary="@string/settings_security_mode_summary"
+            app:defaultValue="true"/>
+
     </PreferenceCategory>
 
 </androidx.preference.PreferenceScreen>