diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index 38921587f9..139a8ab3d2 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -497,6 +497,7 @@ common/views/components/profile-editor.vue:
   account: "アカウント"
   location: "場所"
   description: "自己紹介"
+  language: "言語"
   birthday: "誕生日"
   avatar: "アイコン"
   banner: "バナー"
diff --git a/package.json b/package.json
index c92801174b..7aa9d51a87 100644
--- a/package.json
+++ b/package.json
@@ -156,6 +156,7 @@
 		"koa-send": "5.0.0",
 		"koa-slow": "2.1.0",
 		"koa-views": "6.1.4",
+		"langmap": "0.0.16",
 		"loader-utils": "1.1.0",
 		"minio": "7.0.1",
 		"mkdirp": "0.5.1",
diff --git a/src/client/app/common/views/components/profile-editor.vue b/src/client/app/common/views/components/profile-editor.vue
index b402f046b1..33c53c7dc8 100644
--- a/src/client/app/common/views/components/profile-editor.vue
+++ b/src/client/app/common/views/components/profile-editor.vue
@@ -32,6 +32,12 @@
 				<span>{{ $t('description') }}</span>
 			</ui-textarea>
 
+			<ui-select v-model="lang">
+				<span slot="label">{{ $t('language') }}</span>
+				<span slot="icon"><fa icon="language"/></span>
+				<option v-for="lang in unique(Object.values(langmap).map(x => x.nativeName)).map(name => Object.keys(langmap).find(k => langmap[k].nativeName == name))" :value="lang" :key="lang">{{ langmap[lang].nativeName }}</option>
+			</ui-select>
+
 			<ui-input type="file" @change="onAvatarChange">
 				<span>{{ $t('avatar') }}</span>
 				<span slot="icon"><fa icon="image"/></span>
@@ -87,12 +93,16 @@ import Vue from 'vue';
 import i18n from '../../../i18n';
 import { apiUrl, host } from '../../../config';
 import { toUnicode } from 'punycode';
+import langmap from 'langmap';
+import { unique } from '../../../../../prelude/array';
 
 export default Vue.extend({
 	i18n: i18n('common/views/components/profile-editor.vue'),
 
 	data() {
 		return {
+			unique,
+			langmap,
 			host: toUnicode(host),
 			enableEmail: false,
 			email: null,
@@ -100,6 +110,7 @@ export default Vue.extend({
 			username: null,
 			location: null,
 			description: null,
+			lang: null,
 			birthday: null,
 			avatarId: null,
 			bannerId: null,
@@ -137,6 +148,7 @@ export default Vue.extend({
 		this.username = this.$store.state.i.username;
 		this.location = this.$store.state.i.profile.location;
 		this.description = this.$store.state.i.description;
+		this.lang = this.$store.state.i.lang;
 		this.birthday = this.$store.state.i.profile.birthday;
 		this.avatarId = this.$store.state.i.avatarId;
 		this.bannerId = this.$store.state.i.bannerId;
@@ -198,6 +210,7 @@ export default Vue.extend({
 				name: this.name || null,
 				location: this.location || null,
 				description: this.description || null,
+				lang: this.lang,
 				birthday: this.birthday || null,
 				avatarId: this.avatarId || undefined,
 				bannerId: this.bannerId || undefined,
diff --git a/src/models/user.ts b/src/models/user.ts
index 0e9875504b..18e45dbae9 100644
--- a/src/models/user.ts
+++ b/src/models/user.ts
@@ -44,6 +44,7 @@ type IUserBase = {
 	wallpaperUrl?: string;
 	data: any;
 	description: string;
+	lang?: string;
 	pinnedNoteIds: mongo.ObjectID[];
 
 	/**
diff --git a/src/server/api/endpoints/i/update.ts b/src/server/api/endpoints/i/update.ts
index 4952b2f010..b87c3c47e7 100644
--- a/src/server/api/endpoints/i/update.ts
+++ b/src/server/api/endpoints/i/update.ts
@@ -6,6 +6,7 @@ import acceptAllFollowRequests from '../../../../services/following/requests/acc
 import { publishToFollowers } from '../../../../services/i/update';
 import define from '../../define';
 import getDriveFileUrl from '../../../../misc/get-drive-file-url';
+const langmap = require('langmap');
 
 export const meta = {
 	desc: {
@@ -32,6 +33,13 @@ export const meta = {
 			}
 		},
 
+		lang: {
+			validator: $.str.optional.nullable.or(Object.keys(langmap)),
+			desc: {
+				'ja-JP': '言語'
+			}
+		},
+
 		location: {
 			validator: $.str.optional.nullable.pipe(isValidLocation),
 			desc: {
@@ -121,6 +129,7 @@ export default define(meta, (ps, user, app) => new Promise(async (res, rej) => {
 
 	if (ps.name !== undefined) updates.name = ps.name;
 	if (ps.description !== undefined) updates.description = ps.description;
+	if (ps.lang !== undefined) updates.lang = ps.lang;
 	if (ps.location !== undefined) updates['profile.location'] = ps.location;
 	if (ps.birthday !== undefined) updates['profile.birthday'] = ps.birthday;
 	if (ps.avatarId !== undefined) updates.avatarId = ps.avatarId;