diff --git a/CHANGELOG.md b/CHANGELOG.md
index d549cf9545..9bafcebfa5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@
 - Enhance: ノート詳細画面にロールのバッジを表示
 - Enhance: 過去に送信したフォローリクエストを確認できるように  
   (Based on https://activitypub.software/TransFem-org/Sharkey/-/merge_requests/663)
+- Enhance: サイドバーを簡単に展開・折りたたみできるように ( #14981 )
 - Fix: 通知の範囲指定の設定項目が必要ない通知設定でも範囲指定の設定がでている問題を修正
 - Fix: Turnstileが失敗・期限切れした際にも成功扱いとなってしまう問題を修正  
   (Cherry-picked from https://github.com/MisskeyIO/misskey/pull/768)
diff --git a/packages/frontend/src/pages/settings/navbar.vue b/packages/frontend/src/pages/settings/navbar.vue
index b189db0f8f..c38cdc4fc2 100644
--- a/packages/frontend/src/pages/settings/navbar.vue
+++ b/packages/frontend/src/pages/settings/navbar.vue
@@ -100,10 +100,6 @@ function reset() {
 	}));
 }
 
-watch(menuDisplay, async () => {
-	await reloadAsk({ reason: i18n.ts.reloadToApplySetting, unison: true });
-});
-
 const headerActions = computed(() => []);
 
 const headerTabs = computed(() => []);
diff --git a/packages/frontend/src/ui/_common_/navbar.vue b/packages/frontend/src/ui/_common_/navbar.vue
index 8ae11efa2c..8fc76741e3 100644
--- a/packages/frontend/src/ui/_common_/navbar.vue
+++ b/packages/frontend/src/ui/_common_/navbar.vue
@@ -56,6 +56,21 @@ SPDX-License-Identifier: AGPL-3.0-only
 			</button>
 		</div>
 	</div>
+	<button v-if="!forceIconOnly" class="_button" :class="$style.toggleButton" @click="toggleIconOnly">
+		<!--
+		<svg viewBox="0 0 16 48" :class="$style.toggleButtonShape">
+			<g transform="matrix(0.333333,0,0,0.222222,0.000895785,13.3333)">
+				<path d="M23.935,-24C37.223,-24 47.995,-7.842 47.995,12.09C47.995,34.077 47.995,62.07 47.995,84.034C47.995,93.573 45.469,102.721 40.972,109.466C36.475,116.211 30.377,120 24.018,120L23.997,120C10.743,120 -0.003,136.118 -0.003,156C-0.003,156 -0.003,156 -0.003,156L-0.003,-60L-0.003,-59.901C-0.003,-50.379 2.519,-41.248 7.007,-34.515C11.496,-27.782 17.584,-24 23.931,-24C23.932,-24 23.934,-24 23.935,-24Z" style="fill:var(--MI_THEME-navBg);"/>
+			</g>
+		</svg>
+		-->
+		<svg viewBox="0 0 16 64" :class="$style.toggleButtonShape">
+			<g transform="matrix(0.333333,0,0,0.222222,0.000895785,21.3333)">
+				<path d="M47.488,7.995C47.79,10.11 47.943,12.266 47.943,14.429C47.997,26.989 47.997,84 47.997,84C47.997,84 44.018,118.246 23.997,133.5C-0.374,152.07 -0.003,192 -0.003,192L-0.003,-96C-0.003,-96 0.151,-56.216 23.997,-37.5C40.861,-24.265 46.043,-1.243 47.488,7.995Z" style="fill:var(--MI_THEME-navBg);"/>
+			</g>
+		</svg>
+		<i :class="'ti ' + `ti-chevron-${ iconOnly ? 'right' : 'left' }`" style="font-size: 12px; margin-left: -8px;"></i>
+	</button>
 </div>
 </template>
 
@@ -80,9 +95,11 @@ const otherMenuItemIndicated = computed(() => {
 	return false;
 });
 
-const calcViewState = () => {
-	iconOnly.value = (window.innerWidth <= 1279) || (defaultStore.state.menuDisplay === 'sideIcon');
-};
+const forceIconOnly = window.innerWidth <= 1279;
+
+function calcViewState() {
+	iconOnly.value = forceIconOnly || (defaultStore.state.menuDisplay === 'sideIcon');
+}
 
 calcViewState();
 
@@ -92,6 +109,10 @@ watch(defaultStore.reactiveState.menuDisplay, () => {
 	calcViewState();
 });
 
+function toggleIconOnly() {
+	defaultStore.set('menuDisplay', iconOnly.value ? 'sideFull' : 'sideIcon');
+}
+
 function openAccountMenu(ev: MouseEvent) {
 	openAccountMenu_({
 		withExtraOperation: true,
@@ -133,6 +154,38 @@ function more(ev: MouseEvent) {
 	contain: strict;
 	display: flex;
 	flex-direction: column;
+	direction: rtl; // スクロールバーを左に表示したいため
+}
+
+.top {
+	direction: ltr;
+}
+
+.middle {
+	direction: ltr;
+}
+
+.bottom {
+	direction: ltr;
+}
+
+.toggleButton {
+	position: fixed;
+	bottom: 20px;
+	left: var(--nav-width);
+	z-index: 1001;
+	width: 16px;
+	height: 64px;
+	box-sizing: border-box;
+}
+
+.toggleButtonShape {
+	position: absolute;
+	z-index: -1;
+	top: 0;
+	left: 0;
+	width: 16px;
+	height: 64px;
 }
 
 .root:not(.iconOnly) {
@@ -363,6 +416,10 @@ function more(ev: MouseEvent) {
 		position: relative;
 		font-size: 0.9em;
 	}
+
+	.toggleButton {
+		left: var(--nav-width);
+	}
 }
 
 .root.iconOnly {
@@ -563,5 +620,9 @@ function more(ev: MouseEvent) {
 			font-size: 10px;
 		}
 	}
+
+	.toggleButton {
+		left: var(--nav-icon-only-width);
+	}
 }
 </style>