diff --git a/locales/index.d.ts b/locales/index.d.ts
index 60e88a2192..3e34c6a813 100644
--- a/locales/index.d.ts
+++ b/locales/index.d.ts
@@ -609,6 +609,7 @@ export interface Locale {
     "enablePlayer": string;
     "disablePlayer": string;
     "expandTweet": string;
+    "expandNote": string;
     "themeEditor": string;
     "description": string;
     "describeFile": string;
diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index 3d31dcef49..b1838fa5ab 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -606,6 +606,7 @@ useCw: "内容を隠す"
 enablePlayer: "プレイヤーを開く"
 disablePlayer: "プレイヤーを閉じる"
 expandTweet: "ポストを展開する"
+expandNote: "ノートを展開する"
 themeEditor: "テーマエディター"
 description: "説明"
 describeFile: "キャプションを付ける"
diff --git a/packages/frontend/src/components/MkNote.vue b/packages/frontend/src/components/MkNote.vue
index 7d4207f0fb..515a002680 100644
--- a/packages/frontend/src/components/MkNote.vue
+++ b/packages/frontend/src/components/MkNote.vue
@@ -83,7 +83,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 					</div>
 					<MkPoll v-if="appearNote.poll" :note="appearNote" :class="$style.poll"/>
 					<MkUrlPreview v-for="url in urls" :key="url" :url="url" :compact="true" :detail="false" :class="$style.urlPreview"/>
-					<div v-if="appearNote.renote" :class="$style.quote"><MkNoteSimple :note="appearNote.renote" :class="$style.quoteNote"/></div>
+					<MkNoteSimple v-if="appearNote.renote" :note="appearNote.renote" :quoted="true"/>
 					<button v-if="isLong && collapsed" :class="$style.collapsed" class="_button" @click="collapsed = false">
 						<span :class="$style.collapsedLabel">{{ i18n.ts.showMore }}</span>
 					</button>
@@ -800,17 +800,6 @@ function emitUpdReaction(emoji: string, delta: number) {
 	font-size: 80%;
 }
 
-.quote {
-	padding: 8px 0;
-}
-
-.quoteNote {
-	padding: 16px;
-	border: dashed 1px var(--renote);
-	border-radius: 8px;
-	overflow: clip;
-}
-
 .channel {
 	opacity: 0.7;
 	font-size: 80%;
@@ -947,12 +936,6 @@ function emitUpdReaction(emoji: string, delta: number) {
 	}
 }
 
-@container (max-width: 250px) {
-	.quoteNote {
-		padding: 12px;
-	}
-}
-
 .muted {
 	padding: 8px;
 	text-align: center;
diff --git a/packages/frontend/src/components/MkNoteSimple.vue b/packages/frontend/src/components/MkNoteSimple.vue
index e7cb3f96f1..4488cdcff3 100644
--- a/packages/frontend/src/components/MkNoteSimple.vue
+++ b/packages/frontend/src/components/MkNoteSimple.vue
@@ -4,7 +4,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 -->
 
 <template>
-<div :class="$style.root">
+<div :class="[$style.root, quoted ? $style.quoted : null]">
 	<MkAvatar :class="$style.avatar" :user="note.user" link preview/>
 	<div :class="$style.main">
 		<MkNoteHeader :class="$style.header" :note="note" :mini="true"/>
@@ -30,6 +30,8 @@ import MkCwButton from '@/components/MkCwButton.vue';
 
 const props = defineProps<{
 	note: Misskey.entities.Note;
+	pinned?: boolean;
+	quoted?: boolean;
 }>();
 
 const showContent = ref(false);
@@ -78,12 +80,24 @@ const showContent = ref(false);
 	padding: 0;
 }
 
+.quoted {
+	margin: 8px 0;
+	padding: 16px;
+	border: dashed 1px var(--renote);
+	border-radius: 8px;
+	overflow: clip;
+}
+
 @container (min-width: 250px) {
 	.avatar {
 		margin: 0 10px 0 0;
 		width: 40px;
 		height: 40px;
 	}
+
+	.quoted {
+		padding: 12px;
+	}
 }
 
 @container (min-width: 350px) {
diff --git a/packages/frontend/src/components/MkUrlPreview.vue b/packages/frontend/src/components/MkUrlPreview.vue
index f0f1a13d0b..00c4f68858 100644
--- a/packages/frontend/src/components/MkUrlPreview.vue
+++ b/packages/frontend/src/components/MkUrlPreview.vue
@@ -26,8 +26,8 @@ SPDX-License-Identifier: AGPL-3.0-only
 		</MkButton>
 	</div>
 </template>
-<template v-else-if="tweetId && tweetExpanded">
-	<div ref="twitter">
+<template v-else-if="postExpanded">
+	<div v-if="tweetId" ref="twitter">
 		<iframe
 			ref="tweet"
 			allow="fullscreen;web-share"
@@ -37,9 +37,10 @@ SPDX-License-Identifier: AGPL-3.0-only
 			:src="`https://platform.twitter.com/embed/index.html?embedId=${embedId}&amp;hideCard=false&amp;hideThread=false&amp;lang=en&amp;theme=${defaultStore.state.darkMode ? 'dark' : 'light'}&amp;id=${tweetId}`"
 		></iframe>
 	</div>
+	<MkNoteSimple v-else-if="note" :note="note" :quoted="true"/>
 	<div :class="$style.action">
-		<MkButton :small="true" inline @click="tweetExpanded = false">
-			<i class="ti ti-x"></i> {{ i18n.ts.close }}
+		<MkButton :small="true" inline @click="postExpanded = false">
+			<i v-if="tweetId" class="ti ti-x"></i> {{ i18n.ts.close }}
 		</MkButton>
 	</div>
 </template>
@@ -66,10 +67,15 @@ SPDX-License-Identifier: AGPL-3.0-only
 	</component>
 	<template v-if="showActions">
 		<div v-if="tweetId" :class="$style.action">
-			<MkButton :small="true" inline @click="tweetExpanded = true">
+			<MkButton :small="true" inline @click="postExpanded = true">
 				<i class="ti ti-brand-x"></i> {{ i18n.ts.expandTweet }}
 			</MkButton>
 		</div>
+		<div v-if="noteUrl || note" :class="$style.action">
+			<MkButton :small="true" inline @click="resolveNote()">
+				{{ i18n.ts.expandNote }}
+			</MkButton>
+		</div>
 		<div v-if="!playerEnabled && player.url" :class="$style.action">
 			<MkButton :small="true" inline @click="playerEnabled = true">
 				<i class="ti ti-player-play"></i> {{ i18n.ts.enablePlayer }}
@@ -85,11 +91,13 @@ SPDX-License-Identifier: AGPL-3.0-only
 <script lang="ts" setup>
 import { defineAsyncComponent, onUnmounted, ref } from 'vue';
 import type { summaly } from 'summaly';
+import type * as Misskey from 'misskey-js';
 import { url as local } from '@/config.js';
 import { i18n } from '@/i18n.js';
 import * as os from '@/os.js';
 import { deviceKind } from '@/scripts/device-kind.js';
 import MkButton from '@/components/MkButton.vue';
+import MkNoteSimple from '@/components/MkNoteSimple.vue';
 import { versatileLang } from '@/scripts/intl-const.js';
 import { defaultStore } from '@/store.js';
 
@@ -126,7 +134,9 @@ const player = ref({
 } as SummalyResult['player']);
 const playerEnabled = ref(false);
 const tweetId = ref<string | null>(null);
-const tweetExpanded = ref(props.detail);
+const noteUrl = ref<string | null>(null);
+const note = ref<Misskey.entities.Note | null>(null);
+const postExpanded = ref(props.detail);
 const embedId = `embed${Math.random().toString().replace(/\D/, '')}`;
 const tweetHeight = ref(150);
 const unknownUrl = ref(false);
@@ -172,9 +182,40 @@ window.fetch(`/url?url=${encodeURIComponent(requestUrl.href)}&lang=${versatileLa
 		sitename.value = info.sitename;
 		player.value = info.player;
 		sensitive.value = info.sensitive ?? false;
+		noteUrl.value = info.activityPub;
+		if (postExpanded.value) {
+			resolveNote();
+		}
 	});
 
-function adjustTweetHeight(message: any) {
+async function resolveNote(): Promise<void> {
+	if (note.value) {
+		// Reuse the data
+		postExpanded.value = true;
+		return;
+	}
+	if (!noteUrl.value) {
+		// Note does not exist
+		return;
+	}
+
+	try {
+		fetching.value = true;
+		const result = await os.api('ap/show', { uri: noteUrl.value });
+		if (result.type === 'Note') {
+			note.value = result.object;
+			postExpanded.value = true;
+		} else {
+			postExpanded.value = false;
+		}
+	} finally {
+		// Prevent repeated resolving
+		noteUrl.value = null;
+		fetching.value = false;
+	}
+}
+
+function adjustTweetHeight(message: any): void {
 	if (message.origin !== 'https://platform.twitter.com') return;
 	const embed = message.data?.['twttr.embed'];
 	if (embed?.method !== 'twttr.private.resize') return;
diff --git a/packages/frontend/test/url-preview.test.ts b/packages/frontend/test/url-preview.test.ts
index f760de9274..92762472d0 100644
--- a/packages/frontend/test/url-preview.test.ts
+++ b/packages/frontend/test/url-preview.test.ts
@@ -3,10 +3,11 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { describe, test, assert, afterEach } from 'vitest';
+import { describe, test, assert, afterEach, beforeAll, vi } from 'vitest';
 import { render, cleanup, type RenderResult } from '@testing-library/vue';
 import './init';
 import type { summaly } from 'summaly';
+import type * as misskey from 'misskey-js';
 import { components } from '@/components/index.js';
 import { directives } from '@/directives/index.js';
 import MkUrlPreview from '@/components/MkUrlPreview.vue';
@@ -47,13 +48,18 @@ describe('MkUrlPreview', () => {
 		return result;
 	};
 
-	const renderAndOpenPreview = async (summary: Partial<SummalyResult>): Promise<HTMLIFrameElement | null> => {
+	const renderAndOpenPreview = async (summary: Partial<SummalyResult>): Promise<RenderResult> => {
 		const mkUrlPreview = await renderPreviewBy(summary);
 		const buttons = mkUrlPreview.getAllByRole('button');
 		buttons[0].click();
 		// Wait for the click event to be fired
 		await Promise.resolve();
 
+		return mkUrlPreview;
+	};
+
+	const renderAndOpenPreviewInIFrame = async (summary: Partial<SummalyResult>): Promise<HTMLIFrameElement | null> => {
+		const mkUrlPreview = await renderAndOpenPreview(summary);
 		return mkUrlPreview.container.querySelector('iframe');
 	};
 
@@ -85,7 +91,7 @@ describe('MkUrlPreview', () => {
 	});
 
 	test('Having a player should setup the iframe', async () => {
-		const iframe = await renderAndOpenPreview({
+		const iframe = await renderAndOpenPreviewInIFrame({
 			url: 'https://example.local',
 			player: {
 				url: 'https://example.local/player',
@@ -103,7 +109,7 @@ describe('MkUrlPreview', () => {
 	});
 
 	test('Having a player with `allow` field should set permissions', async () => {
-		const iframe = await renderAndOpenPreview({
+		const iframe = await renderAndOpenPreviewInIFrame({
 			url: 'https://example.local',
 			player: {
 				url: 'https://example.local/player',
@@ -117,7 +123,7 @@ describe('MkUrlPreview', () => {
 	});
 
 	test('Having a player width should keep the fixed aspect ratio', async () => {
-		const iframe = await renderAndOpenPreview({
+		const iframe = await renderAndOpenPreviewInIFrame({
 			url: 'https://example.local',
 			player: {
 				url: 'https://example.local/player',
@@ -131,7 +137,7 @@ describe('MkUrlPreview', () => {
 	});
 
 	test('Having a player width should keep the fixed height', async () => {
-		const iframe = await renderAndOpenPreview({
+		const iframe = await renderAndOpenPreviewInIFrame({
 			url: 'https://example.local',
 			player: {
 				url: 'https://example.local/player',
@@ -145,7 +151,7 @@ describe('MkUrlPreview', () => {
 	});
 
 	test('Loading a tweet in iframe', async () => {
-		const iframe = await renderAndOpenPreview({
+		const iframe = await renderAndOpenPreviewInIFrame({
 			url: 'https://twitter.com/i/web/status/1685072521782325249',
 		});
 		assert.exists(iframe, 'iframe should exist');
@@ -154,11 +160,48 @@ describe('MkUrlPreview', () => {
 	});
 
 	test('Loading a post in iframe', async () => {
-		const iframe = await renderAndOpenPreview({
+		const iframe = await renderAndOpenPreviewInIFrame({
 			url: 'https://x.com/i/web/status/1685072521782325249',
 		});
 		assert.exists(iframe, 'iframe should exist');
 		assert.strictEqual(iframe?.getAttribute('allow'), 'fullscreen;web-share');
 		assert.strictEqual(iframe?.getAttribute('sandbox'), 'allow-popups allow-popups-to-escape-sandbox allow-scripts allow-same-origin');
 	});
+
+	describe('ActivityPub notes', () => {
+		afterEach(() => {
+			vi.clearAllMocks();
+		});
+
+		test('Preview a note', async () => {
+			vi.mock('@/os', () => {
+				return {
+					api(endpoint: string): unknown {
+						if (endpoint === 'ap/show') {
+							return {
+								type: 'Note',
+								object: {
+									text: 'Mizuki',
+									createdAt: new Date().toISOString(),
+									user: {},
+									files: [] as misskey.entities.DriveFile[],
+								} as misskey.entities.Note,
+							};
+						}
+						throw new Error(`Unexpected api call ${endpoint}`);
+					},
+				};
+			});
+
+			const url = 'https://example.local';
+			const renderResult = await renderAndOpenPreview({
+				url,
+				description: 'Misskey',
+				activityPub: url,
+			});
+
+			assert.notExists(renderResult.queryByText('Misskey'), 'Original description should disappear');
+			assert.exists(renderResult.queryByText('Mizuki'), 'ActivityPub fetch result should appear');
+		});
+	});
 });