diff --git a/CHANGELOG.md b/CHANGELOG.md
index 95f435b7d7..d5ce885b9b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -69,6 +69,7 @@
 	- 逆に、MFMでコードハイライトを利用したい際は言語を明示的に指定する必要があります  
 	（例: ` ```js ` → Javascript, ` ```ais ` → AiScript）
 -	Enhance: 絵文字などのオートコンプリートでShift+Tabを押すと前の候補を選択できるように
+- Enhance: チャンネルに新規の投稿がある場合にバッジを表示させる
 - Fix: 「設定のバックアップ」で一部の項目がバックアップに含まれていなかった問題を修正
 - Fix: ウィジェットのジョブキューにて音声の発音方法変更に追従できていなかったのを修正 #12367
 - Fix: コードエディタが正しく表示されない問題を修正
diff --git a/packages/frontend/src/components/MkChannelPreview.vue b/packages/frontend/src/components/MkChannelPreview.vue
index 4512f2dd60..bf6504d6bf 100644
--- a/packages/frontend/src/components/MkChannelPreview.vue
+++ b/packages/frontend/src/components/MkChannelPreview.vue
@@ -4,49 +4,70 @@ SPDX-License-Identifier: AGPL-3.0-only
 -->
 
 <template>
-<MkA :to="`/channels/${channel.id}`" class="eftoefju _panel" tabindex="-1">
-	<div class="banner" :style="bannerStyle">
-		<div class="fade"></div>
-		<div class="name"><i class="ti ti-device-tv"></i> {{ channel.name }}</div>
-		<div v-if="channel.isSensitive" class="sensitiveIndicator">{{ i18n.ts.sensitive }}</div>
-		<div class="status">
-			<div>
-				<i class="ti ti-users ti-fw"></i>
-				<I18n :src="i18n.ts._channel.usersCount" tag="span" style="margin-left: 4px;">
-					<template #n>
-						<b>{{ channel.usersCount }}</b>
-					</template>
-				</I18n>
-			</div>
-			<div>
-				<i class="ti ti-pencil ti-fw"></i>
-				<I18n :src="i18n.ts._channel.notesCount" tag="span" style="margin-left: 4px;">
-					<template #n>
-						<b>{{ channel.notesCount }}</b>
-					</template>
-				</I18n>
+<div style="position: relative;">
+	<MkA :to="`/channels/${channel.id}`" class="eftoefju _panel" tabindex="-1" @click="updateLastReadedAt">
+		<div class="banner" :style="bannerStyle">
+			<div class="fade"></div>
+			<div class="name"><i class="ti ti-device-tv"></i> {{ channel.name }}</div>
+			<div v-if="channel.isSensitive" class="sensitiveIndicator">{{ i18n.ts.sensitive }}</div>
+			<div class="status">
+				<div>
+					<i class="ti ti-users ti-fw"></i>
+					<I18n :src="i18n.ts._channel.usersCount" tag="span" style="margin-left: 4px;">
+						<template #n>
+							<b>{{ channel.usersCount }}</b>
+						</template>
+					</I18n>
+				</div>
+				<div>
+					<i class="ti ti-pencil ti-fw"></i>
+					<I18n :src="i18n.ts._channel.notesCount" tag="span" style="margin-left: 4px;">
+						<template #n>
+							<b>{{ channel.notesCount }}</b>
+						</template>
+					</I18n>
+				</div>
 			</div>
 		</div>
-	</div>
-	<article v-if="channel.description">
-		<p :title="channel.description">{{ channel.description.length > 85 ? channel.description.slice(0, 85) + '…' : channel.description }}</p>
-	</article>
-	<footer>
-		<span v-if="channel.lastNotedAt">
-			{{ i18n.ts.updatedAt }}: <MkTime :time="channel.lastNotedAt"/>
-		</span>
-	</footer>
-</MkA>
+		<article v-if="channel.description">
+			<p :title="channel.description">{{ channel.description.length > 85 ? channel.description.slice(0, 85) + '…' : channel.description }}</p>
+		</article>
+		<footer>
+			<span v-if="channel.lastNotedAt">
+				{{ i18n.ts.updatedAt }}: <MkTime :time="channel.lastNotedAt"/>
+			</span>
+		</footer>
+	</MkA>
+	<div
+		v-if="channel.lastNotedAt && (channel.isFavorited || channel.isFollowing) && (!lastReadedAt || Date.parse(channel.lastNotedAt) > lastReadedAt)"
+		class="indicator"
+	></div>
+</div>
 </template>
 
 <script lang="ts" setup>
-import { computed } from 'vue';
+import { computed, ref, watch } from 'vue';
 import { i18n } from '@/i18n.js';
+import { miLocalStorage } from '@/local-storage.js';
 
 const props = defineProps<{
 	channel: Record<string, any>;
 }>();
 
+const getLastReadedAt = (): number | null => {
+	return miLocalStorage.getItemAsJson(`channelLastReadedAt:${props.channel.id}`) ?? null;
+};
+
+const lastReadedAt = ref(getLastReadedAt());
+
+watch(() => props.channel.id, () => {
+	lastReadedAt.value = getLastReadedAt();
+});
+
+const updateLastReadedAt = () => {
+	lastReadedAt.value = props.channel.lastNotedAt ? Date.parse(props.channel.lastNotedAt) : Date.now();
+};
+
 const bannerStyle = computed(() => {
 	if (props.channel.bannerUrl) {
 		return { backgroundImage: `url(${props.channel.bannerUrl})` };
@@ -170,4 +191,17 @@ const bannerStyle = computed(() => {
 	}
 }
 
+.indicator {
+	position: absolute;
+	top: 0;
+	right: 0;
+	transform: translate(25%, -25%);
+	background-color: var(--accent);
+	border: solid var(--bg) 4px;
+	border-radius: 100%;
+	width: 1.5rem;
+	height: 1.5rem;
+	aspect-ratio: 1 / 1;
+}
+
 </style>
diff --git a/packages/frontend/src/components/MkMenu.vue b/packages/frontend/src/components/MkMenu.vue
index 8e4b86f1c7..0a97cf3dba 100644
--- a/packages/frontend/src/components/MkMenu.vue
+++ b/packages/frontend/src/components/MkMenu.vue
@@ -15,7 +15,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 		<template v-for="(item, i) in items2">
 			<div v-if="item.type === 'divider'" role="separator" :class="$style.divider"></div>
 			<span v-else-if="item.type === 'label'" role="menuitem" :class="[$style.label, $style.item]">
-				<span>{{ item.text }}</span>
+				<span style="opacity: 0.7;">{{ item.text }}</span>
 			</span>
 			<span v-else-if="item.type === 'pending'" role="menuitem" :tabindex="i" :class="[$style.pending, $style.item]">
 				<span><MkEllipsis/></span>
@@ -23,32 +23,44 @@ SPDX-License-Identifier: AGPL-3.0-only
 			<MkA v-else-if="item.type === 'link'" role="menuitem" :to="item.to" :tabindex="i" class="_button" :class="$style.item" @click.passive="close(true)" @mouseenter.passive="onItemMouseEnter(item)" @mouseleave.passive="onItemMouseLeave(item)">
 				<i v-if="item.icon" class="ti-fw" :class="[$style.icon, item.icon]"></i>
 				<MkAvatar v-if="item.avatar" :user="item.avatar" :class="$style.avatar"/>
-				<span>{{ item.text }}</span>
-				<span v-if="item.indicate" :class="$style.indicator"><i class="_indicatorCircle"></i></span>
+				<div :class="$style.item_content">
+					<span :class="$style.item_content_text">{{ item.text }}</span>
+					<span v-if="item.indicate" :class="$style.indicator"><i class="_indicatorCircle"></i></span>
+				</div>
 			</MkA>
 			<a v-else-if="item.type === 'a'" role="menuitem" :href="item.href" :target="item.target" :download="item.download" :tabindex="i" class="_button" :class="$style.item" @click="close(true)" @mouseenter.passive="onItemMouseEnter(item)" @mouseleave.passive="onItemMouseLeave(item)">
 				<i v-if="item.icon" class="ti-fw" :class="[$style.icon, item.icon]"></i>
-				<span>{{ item.text }}</span>
-				<span v-if="item.indicate" :class="$style.indicator"><i class="_indicatorCircle"></i></span>
+				<div :class="$style.item_content">
+					<span :class="$style.item_content_text">{{ item.text }}</span>
+					<span v-if="item.indicate" :class="$style.indicator"><i class="_indicatorCircle"></i></span>
+				</div>
 			</a>
 			<button v-else-if="item.type === 'user'" role="menuitem" :tabindex="i" class="_button" :class="[$style.item, { [$style.active]: item.active }]" :disabled="item.active" @click="clicked(item.action, $event)" @mouseenter.passive="onItemMouseEnter(item)" @mouseleave.passive="onItemMouseLeave(item)">
 				<MkAvatar :user="item.user" :class="$style.avatar"/><MkUserName :user="item.user"/>
-				<span v-if="item.indicate" :class="$style.indicator"><i class="_indicatorCircle"></i></span>
+				<div v-if="item.indicate" :class="$style.item_content">
+					<span :class="$style.indicator"><i class="_indicatorCircle"></i></span>
+				</div>
 			</button>
 			<button v-else-if="item.type === 'switch'" role="menuitemcheckbox" :tabindex="i" class="_button" :class="[$style.item, $style.switch, { [$style.switchDisabled]: item.disabled } ]" @click="switchItem(item)" @mouseenter.passive="onItemMouseEnter(item)" @mouseleave.passive="onItemMouseLeave(item)">
 				<MkSwitchButton :class="$style.switchButton" :checked="item.ref" :disabled="item.disabled" @toggle="switchItem(item)"/>
-				<span :class="$style.switchText">{{ item.text }}</span>
+				<div :class="$style.item_content">
+					<span :class="[$style.item_content_text, $style.switchText]">{{ item.text }}</span>
+				</div>
 			</button>
 			<button v-else-if="item.type === 'parent'" class="_button" role="menuitem" :tabindex="i" :class="[$style.item, $style.parent, { [$style.childShowing]: childShowingItem === item }]" @mouseenter="preferClick ? null : showChildren(item, $event)" @click="!preferClick ? null : showChildren(item, $event)">
 				<i v-if="item.icon" class="ti-fw" :class="[$style.icon, item.icon]" style="pointer-events: none;"></i>
-				<span style="pointer-events: none;">{{ item.text }}</span>
-				<span :class="$style.caret" style="pointer-events: none;"><i class="ti ti-chevron-right ti-fw"></i></span>
+				<div :class="$style.item_content">
+					<span :class="$style.item_content_text" style="pointer-events: none;">{{ item.text }}</span>
+					<span :class="$style.caret" style="pointer-events: none;"><i class="ti ti-chevron-right ti-fw"></i></span>
+				</div>
 			</button>
 			<button v-else :tabindex="i" class="_button" role="menuitem" :class="[$style.item, { [$style.danger]: item.danger, [$style.active]: item.active }]" :disabled="item.active" @click="clicked(item.action, $event)" @mouseenter.passive="onItemMouseEnter(item)" @mouseleave.passive="onItemMouseLeave(item)">
 				<i v-if="item.icon" class="ti-fw" :class="[$style.icon, item.icon]"></i>
 				<MkAvatar v-if="item.avatar" :user="item.avatar" :class="$style.avatar"/>
-				<span>{{ item.text }}</span>
-				<span v-if="item.indicate" :class="$style.indicator"><i class="_indicatorCircle"></i></span>
+				<div :class="$style.item_content">
+					<span :class="$style.item_content_text">{{ item.text }}</span>
+					<span v-if="item.indicate" :class="$style.indicator"><i class="_indicatorCircle"></i></span>
+				</div>
 			</button>
 		</template>
 		<span v-if="items2.length === 0" :class="[$style.none, $style.item]">
@@ -228,6 +240,7 @@ onBeforeUnmount(() => {
 .root {
 	padding: 8px 0;
 	box-sizing: border-box;
+	max-width: 100vw;
 	min-width: 200px;
 	overflow: auto;
 	overscroll-behavior: contain;
@@ -267,7 +280,8 @@ onBeforeUnmount(() => {
 }
 
 .item {
-	display: block;
+	display: flex;
+	align-items: center;
 	position: relative;
 	padding: 5px 16px;
 	width: 100%;
@@ -340,10 +354,6 @@ onBeforeUnmount(() => {
 		pointer-events: none;
 		font-size: 0.7em;
 		padding-bottom: 4px;
-
-		> span {
-			opacity: 0.7;
-		}
 	}
 
 	&.pending {
@@ -373,6 +383,22 @@ onBeforeUnmount(() => {
 	}
 }
 
+.item_content {
+	width: 100%;
+	max-width: 100vw;
+	display: flex;
+	align-items: center;
+	justify-content: space-between;
+	gap: 8px;
+	text-overflow: ellipsis;
+}
+
+.item_content_text {
+	max-width: calc(100vw - 4rem);
+	text-overflow: ellipsis;
+	overflow: hidden;
+}
+
 .switch {
 	position: relative;
 	display: flex;
@@ -406,6 +432,7 @@ onBeforeUnmount(() => {
 
 .icon {
 	margin-right: 8px;
+	line-height: 1;
 }
 
 .caret {
@@ -419,9 +446,8 @@ onBeforeUnmount(() => {
 }
 
 .indicator {
-	position: absolute;
-	top: 5px;
-	left: 13px;
+	display: flex;
+	align-items: center;
 	color: var(--indicator);
 	font-size: 12px;
 	animation: blink 1s infinite;
diff --git a/packages/frontend/src/local-storage.ts b/packages/frontend/src/local-storage.ts
index 0d73885b68..1ef115978e 100644
--- a/packages/frontend/src/local-storage.ts
+++ b/packages/frontend/src/local-storage.ts
@@ -35,7 +35,8 @@ type Keys =
 	`themes:${string}` |
 	`aiscript:${string}` |
 	'lastEmojisFetchedAt' | // DEPRECATED, stored in indexeddb (13.9.0~)
-	'emojis' // DEPRECATED, stored in indexeddb (13.9.0~);
+	'emojis' | // DEPRECATED, stored in indexeddb (13.9.0~);
+	`channelLastReadedAt:${string}`
 
 export const miLocalStorage = {
 	getItem: (key: Keys): string | null => window.localStorage.getItem(key),
diff --git a/packages/frontend/src/pages/channel.vue b/packages/frontend/src/pages/channel.vue
index 698f7fa383..421895ea6c 100644
--- a/packages/frontend/src/pages/channel.vue
+++ b/packages/frontend/src/pages/channel.vue
@@ -12,7 +12,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 				<XChannelFollowButton :channel="channel" :full="true" :class="$style.subscribe"/>
 				<MkButton v-if="favorited" v-tooltip="i18n.ts.unfavorite" asLike class="button" rounded primary :class="$style.favorite" @click="unfavorite()"><i class="ti ti-star"></i></MkButton>
 				<MkButton v-else v-tooltip="i18n.ts.favorite" asLike class="button" rounded :class="$style.favorite" @click="favorite()"><i class="ti ti-star"></i></MkButton>
-				<div :style="{ backgroundImage: channel.bannerUrl ? `url(${channel.bannerUrl})` : null }" :class="$style.banner">
+				<div :style="{ backgroundImage: channel.bannerUrl ? `url(${channel.bannerUrl})` : undefined }" :class="$style.banner">
 					<div :class="$style.bannerStatus">
 						<div><i class="ti ti-users ti-fw"></i><I18n :src="i18n.ts._channel.usersCount" tag="span" style="margin-left: 4px;"><template #n><b>{{ channel.usersCount }}</b></template></I18n></div>
 						<div><i class="ti ti-pencil ti-fw"></i><I18n :src="i18n.ts._channel.notesCount" tag="span" style="margin-left: 4px;"><template #n><b>{{ channel.notesCount }}</b></template></I18n></div>
@@ -27,7 +27,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 			<MkFoldableSection>
 				<template #header><i class="ti ti-pin ti-fw" style="margin-right: 0.5em;"></i>{{ i18n.ts.pinnedNotes }}</template>
-				<div v-if="channel.pinnedNotes.length > 0" class="_gaps">
+				<div v-if="channel.pinnedNotes && channel.pinnedNotes.length > 0" class="_gaps">
 					<MkNote v-for="note in channel.pinnedNotes" :key="note.id" class="_panel" :note="note"/>
 				</div>
 			</MkFoldableSection>
@@ -38,7 +38,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 			<!-- スマホ・タブレットの場合、キーボードが表示されると投稿が見づらくなるので、デスクトップ場合のみ自動でフォーカスを当てる -->
 			<MkPostForm v-if="$i && defaultStore.reactiveState.showFixedPostFormInChannel.value" :channel="channel" class="post-form _panel" fixed :autofocus="deviceKind === 'desktop'"/>
 
-			<MkTimeline :key="channelId" src="channel" :channel="channelId" @before="before" @after="after"/>
+			<MkTimeline :key="channelId" src="channel" :channel="channelId" @before="before" @after="after" @note="miLocalStorage.setItemAsJson(`channelLastReadedAt:${channel.id}`, Date.now())"/>
 		</div>
 		<div v-else-if="tab === 'featured'">
 			<MkNotes :pagination="featuredPagination"/>
@@ -69,6 +69,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <script lang="ts" setup>
 import { computed, watch, ref } from 'vue';
+import * as Misskey from 'misskey-js';
 import MkPostForm from '@/components/MkPostForm.vue';
 import MkTimeline from '@/components/MkTimeline.vue';
 import XChannelFollowButton from '@/components/MkChannelFollowButton.vue';
@@ -89,6 +90,7 @@ import MkFoldableSection from '@/components/MkFoldableSection.vue';
 import { PageHeaderItem } from '@/types/page-header.js';
 import { isSupportShare } from '@/scripts/navigator.js';
 import copyToClipboard from '@/scripts/copy-to-clipboard.js';
+import { miLocalStorage } from '@/local-storage.js';
 
 const router = useRouter();
 
@@ -97,7 +99,7 @@ const props = defineProps<{
 }>();
 
 const tab = ref('overview');
-const channel = ref(null);
+const channel = ref<Misskey.entities.Channel | null>(null);
 const favorited = ref(false);
 const searchQuery = ref('');
 const searchPagination = ref();
@@ -114,14 +116,23 @@ watch(() => props.channelId, async () => {
 	channel.value = await os.api('channels/show', {
 		channelId: props.channelId,
 	});
-	favorited.value = channel.value.isFavorited;
+	favorited.value = channel.value.isFavorited ?? false;
 	if (favorited.value || channel.value.isFollowing) {
 		tab.value = 'timeline';
 	}
+
+	if ((favorited.value || channel.value.isFollowing) && channel.value.lastNotedAt) {
+		const lastReadedAt: number = miLocalStorage.getItemAsJson(`channelLastReadedAt:${channel.value.id}`) ?? 0;
+		const lastNotedAt = Date.parse(channel.value.lastNotedAt);
+
+		if (lastNotedAt > lastReadedAt) {
+			miLocalStorage.setItemAsJson(`channelLastReadedAt:${channel.value.id}`, lastNotedAt);
+		}
+	}
 }, { immediate: true });
 
 function edit() {
-	router.push(`/channels/${channel.value.id}/edit`);
+	router.push(`/channels/${channel.value?.id}/edit`);
 }
 
 function openPostForm() {
@@ -131,6 +142,8 @@ function openPostForm() {
 }
 
 function favorite() {
+	if (!channel.value) return;
+
 	os.apiWithDialog('channels/favorite', {
 		channelId: channel.value.id,
 	}).then(() => {
@@ -139,6 +152,8 @@ function favorite() {
 }
 
 async function unfavorite() {
+	if (!channel.value) return;
+
 	const confirm = await os.confirm({
 		type: 'warning',
 		text: i18n.ts.unfavoriteConfirm,
@@ -152,6 +167,8 @@ async function unfavorite() {
 }
 
 async function search() {
+	if (!channel.value) return;
+
 	const query = searchQuery.value.toString().trim();
 
 	if (query == null) return;
@@ -176,6 +193,10 @@ const headerActions = computed(() => {
 			icon: 'ti ti-link',
 			text: i18n.ts.copyUrl,
 			handler: async (): Promise<void> => {
+				if (!channel.value) {
+					console.warn('failed to copy channel URL. channel.value is null.');
+					return;
+				}
 				copyToClipboard(`${url}/channels/${channel.value.id}`);
 				os.success();
 			},
@@ -186,9 +207,14 @@ const headerActions = computed(() => {
 				icon: 'ti ti-share',
 				text: i18n.ts.share,
 				handler: async (): Promise<void> => {
+					if (!channel.value) {
+						console.warn('failed to share channel. channel.value is null.');
+						return;
+					}
+
 					navigator.share({
 						title: channel.value.name,
-						text: channel.value.description,
+						text: channel.value.description ?? undefined,
 						url: `${url}/channels/${channel.value.id}`,
 					});
 				},
diff --git a/packages/frontend/src/pages/timeline.vue b/packages/frontend/src/pages/timeline.vue
index d976463db4..1b24f98bdb 100644
--- a/packages/frontend/src/pages/timeline.vue
+++ b/packages/frontend/src/pages/timeline.vue
@@ -48,6 +48,7 @@ import { definePageMetadata } from '@/scripts/page-metadata.js';
 import { antennasCache, userListsCache } from '@/cache.js';
 import { deviceKind } from '@/scripts/device-kind.js';
 import { MenuItem } from '@/types/menu.js';
+import { miLocalStorage } from '@/local-storage.js';
 
 provide('shouldOmitHeaderTitle', true);
 
@@ -125,12 +126,17 @@ async function chooseChannel(ev: MouseEvent): Promise<void> {
 		limit: 100,
 	});
 	const items: MenuItem[] = [
-		...channels.map(channel => ({
-			type: 'link' as const,
-			text: channel.name,
-			indicate: channel.hasUnreadNote,
-			to: `/channels/${channel.id}`,
-		})),
+		...channels.map(channel => {
+			const lastReadedAt = miLocalStorage.getItemAsJson(`channelLastReadedAt:${channel.id}`) ?? null;
+			const hasUnreadNote = (lastReadedAt && channel.lastNotedAt) ? Date.parse(channel.lastNotedAt) > lastReadedAt : !!(!lastReadedAt && channel.lastNotedAt);
+
+			return {
+				type: 'link' as const,
+				text: channel.name,
+				indicate: hasUnreadNote,
+				to: `/channels/${channel.id}`,
+			};
+		}),
 		(channels.length === 0 ? undefined : { type: 'divider' }),
 		{
 			type: 'link' as const,