diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4a5f497ddb..9bbc09860e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@
 
 ### Improvements
 - クライアント: アニメーションを減らす設定をメニューのアニメーションにも適用するように
+- クライアント: MFM関数構文のサジェストを実装
 - ActivityPub: HTML -> MFMの変換を強化
 
 ### Bugfixes
diff --git a/src/client/components/autocomplete.vue b/src/client/components/autocomplete.vue
index 065ee6de2e..e2c1af3356 100644
--- a/src/client/components/autocomplete.vue
+++ b/src/client/components/autocomplete.vue
@@ -10,12 +10,12 @@
 		</li>
 		<li @click="chooseUser()" @keydown="onKeydown" tabindex="-1" class="choose">{{ $ts.selectUser }}</li>
 	</ol>
-	<ol class="hashtags" ref="suggests" v-if="hashtags.length > 0">
+	<ol class="hashtags" ref="suggests" v-else-if="hashtags.length > 0">
 		<li v-for="hashtag in hashtags" @click="complete(type, hashtag)" @keydown="onKeydown" tabindex="-1">
 			<span class="name">{{ hashtag }}</span>
 		</li>
 	</ol>
-	<ol class="emojis" ref="suggests" v-if="emojis.length > 0">
+	<ol class="emojis" ref="suggests" v-else-if="emojis.length > 0">
 		<li v-for="emoji in emojis" @click="complete(type, emoji.emoji)" @keydown="onKeydown" tabindex="-1">
 			<span class="emoji" v-if="emoji.isCustomEmoji"><img :src="$store.state.disableShowingAnimatedImages ? getStaticImageUrl(emoji.url) : emoji.url" :alt="emoji.emoji"/></span>
 			<span class="emoji" v-else-if="!$store.state.useOsNativeEmojis"><img :src="emoji.url" :alt="emoji.emoji"/></span>
@@ -24,6 +24,11 @@
 			<span class="alias" v-if="emoji.aliasOf">({{ emoji.aliasOf }})</span>
 		</li>
 	</ol>
+	<ol class="mfmTags" ref="suggests" v-else-if="mfmTags.length > 0">
+		<li v-for="tag in mfmTags" @click="complete(type, tag)" @keydown="onKeydown" tabindex="-1">
+			<span class="tag">{{ tag }}</span>
+		</li>
+	</ol>
 </div>
 </template>
 
@@ -106,6 +111,8 @@ emojiDefinitions.sort((a, b) => a.name.length - b.name.length);
 const emojiDb = markRaw(emojiDefinitions.concat(emjdb));
 //#endregion
 
+const MFM_TAGS = ['tada', 'jelly', 'twitch', 'shake', 'spin', 'jump', 'bounce', 'flip', 'x2', 'x3', 'x4', 'font', 'blur', 'rainbow', 'sparkle'];
+
 export default defineComponent({
 	props: {
 		type: {
@@ -137,11 +144,6 @@ export default defineComponent({
 			type: Number,
 			required: true,
 		},
-
-		showing: {
-			type: Boolean,
-			required: true
-		},
 	},
 
 	emits: ['done', 'closed'],
@@ -154,18 +156,11 @@ export default defineComponent({
 			hashtags: [],
 			emojis: [],
 			items: [],
+			mfmTags: [],
 			select: -1,
 		}
 	},
 
-	watch: {
-		showing() {
-			if (!this.showing) {
-				this.$emit('closed');
-			}
-		}
-	},
-
 	updated() {
 		this.setPosition();
 		this.items = (this.$refs.suggests as Element | undefined)?.children || [];
@@ -236,7 +231,9 @@ export default defineComponent({
 				}
 			}
 
-			if (this.type == 'user') {
+			console.log(this.type);
+
+			if (this.type === 'user') {
 				if (this.q == null) {
 					this.users = [];
 					this.fetching = false;
@@ -262,7 +259,7 @@ export default defineComponent({
 						sessionStorage.setItem(cacheKey, JSON.stringify(users));
 					});
 				}
-			} else if (this.type == 'hashtag') {
+			} else if (this.type === 'hashtag') {
 				if (this.q == null || this.q == '') {
 					this.hashtags = JSON.parse(localStorage.getItem('hashtags') || '[]');
 					this.fetching = false;
@@ -286,7 +283,7 @@ export default defineComponent({
 						});
 					}
 				}
-			} else if (this.type == 'emoji') {
+			} else if (this.type === 'emoji') {
 				if (this.q == null || this.q == '') {
 					// 最近使った絵文字をサジェスト
 					this.emojis = this.$store.state.recentlyUsedEmojis.map(emoji => emojiDb.find(e => e.emoji == emoji)).filter(x => x != null);
@@ -314,6 +311,14 @@ export default defineComponent({
 				}
 
 				this.emojis = matched;
+			} else if (this.type === 'mfmTag') {
+				console.log(this.q);
+				if (this.q == null || this.q == '') {
+					this.mfmTags = MFM_TAGS;
+					return;
+				}
+
+				this.mfmTags = MFM_TAGS.filter(tag => tag.startsWith(this.q));
 			}
 		},
 
@@ -490,5 +495,11 @@ export default defineComponent({
 			margin: 0 0 0 8px;
 		}
 	}
+
+	> .mfmTags > li {
+
+		.name {
+		}
+	}
 }
 </style>
diff --git a/src/client/scripts/autocomplete.ts b/src/client/scripts/autocomplete.ts
index c4bcc4b724..e952ad3907 100644
--- a/src/client/scripts/autocomplete.ts
+++ b/src/client/scripts/autocomplete.ts
@@ -70,11 +70,13 @@ export class Autocomplete {
 		const mentionIndex = text.lastIndexOf('@');
 		const hashtagIndex = text.lastIndexOf('#');
 		const emojiIndex = text.lastIndexOf(':');
+		const mfmTagIndex = text.lastIndexOf('$');
 
 		const max = Math.max(
 			mentionIndex,
 			hashtagIndex,
-			emojiIndex);
+			emojiIndex,
+			mfmTagIndex);
 
 		if (max == -1) {
 			this.close();
@@ -83,6 +85,7 @@ export class Autocomplete {
 
 		const isMention = mentionIndex != -1;
 		const isHashtag = hashtagIndex != -1;
+		const isMfmTag = mfmTagIndex != -1;
 		const isEmoji = emojiIndex != -1 && text.split(/:[a-z0-9_+\-]+:/).pop()!.includes(':');
 
 		let opened = false;
@@ -114,6 +117,14 @@ export class Autocomplete {
 			}
 		}
 
+		if (isMfmTag && !opened) {
+			const mfmTag = text.substr(mfmTagIndex + 1);
+			if (!mfmTag.includes(' ')) {
+				this.open('mfmTag', mfmTag);
+				opened = true;
+			}
+		}
+
 		if (!opened) {
 			this.close();
 		}
@@ -244,6 +255,22 @@ export class Autocomplete {
 				const pos = trimmedBefore.length + value.length;
 				this.textarea.setSelectionRange(pos, pos);
 			});
+		} else if (type == 'mfmTag') {
+			const source = this.text;
+
+			const before = source.substr(0, caret);
+			const trimmedBefore = before.substring(0, before.lastIndexOf('$'));
+			const after = source.substr(caret);
+
+			// 挿入
+			this.text = `${trimmedBefore}$[${value} ]${after}`;
+
+			// キャレットを戻す
+			this.vm.$nextTick(() => {
+				this.textarea.focus();
+				const pos = trimmedBefore.length + (value.length + 3);
+				this.textarea.setSelectionRange(pos, pos);
+			});
 		}
 	}
 }