diff --git a/src/client/app/desktop/views/pages/user/user.header.vue b/src/client/app/desktop/views/pages/user/user.header.vue
index 629f6d87cf..a003731174 100644
--- a/src/client/app/desktop/views/pages/user/user.header.vue
+++ b/src/client/app/desktop/views/pages/user/user.header.vue
@@ -2,8 +2,8 @@
 <div class="header" :data-is-dark-background="user.bannerUrl != null">
 	<div class="is-suspended" v-if="user.isSuspended"><p>%fa:exclamation-triangle% %i18n:@is-suspended%</p></div>
 	<div class="is-remote" v-if="user.host != null"><p>%fa:exclamation-triangle% %i18n:@is-remote%<a :href="user.url || user.uri" target="_blank">%i18n:@view-remote%</a></p></div>
-	<div class="banner-container" :style="user.bannerUrl ? `background-image: url(${user.bannerUrl}?thumbnail&size=2048)` : ''">
-		<div class="banner" ref="banner" :style="user.bannerUrl ? `background-image: url(${user.bannerUrl}?thumbnail&size=2048)` : ''" @click="onBannerClick"></div>
+	<div class="banner-container" :style="user.bannerUrl ? `background-image: url(${user.bannerUrl})` : ''">
+		<div class="banner" ref="banner" :style="user.bannerUrl ? `background-image: url(${user.bannerUrl})` : ''" @click="onBannerClick"></div>
 		<div class="fade"></div>
 	</div>
 	<div class="container">
diff --git a/src/client/app/mobile/views/pages/user.vue b/src/client/app/mobile/views/pages/user.vue
index e50086b5fd..c602a26388 100644
--- a/src/client/app/mobile/views/pages/user.vue
+++ b/src/client/app/mobile/views/pages/user.vue
@@ -5,7 +5,7 @@
 		<div class="is-suspended" v-if="user.isSuspended"><p>%fa:exclamation-triangle% %i18n:@is-suspended%</p></div>
 		<div class="is-remote" v-if="user.host != null"><p>%fa:exclamation-triangle% %i18n:@is-remote%<a :href="user.url || user.uri" target="_blank">%i18n:@view-remote%</a></p></div>
 		<header>
-			<div class="banner" :style="user.bannerUrl ? `background-image: url(${user.bannerUrl}?thumbnail&size=1024)` : ''"></div>
+			<div class="banner" :style="user.bannerUrl ? `background-image: url(${user.bannerUrl})` : ''"></div>
 			<div class="body">
 				<div class="top">
 					<a class="avatar">
diff --git a/src/drive/gen-thumbnail.ts b/src/drive/gen-thumbnail.ts
new file mode 100644
index 0000000000..455705cd3a
--- /dev/null
+++ b/src/drive/gen-thumbnail.ts
@@ -0,0 +1,25 @@
+import * as stream from 'stream';
+import * as Gm from 'gm';
+import { IDriveFile, getDriveFileBucket } from '../models/drive-file';
+
+const gm = Gm.subClass({
+	imageMagick: true
+});
+
+export default async function(file: IDriveFile): Promise<stream.Readable> {
+	if (!/^image\/.*$/.test(file.contentType)) return null;
+
+	const bucket = await getDriveFileBucket();
+	const readable = bucket.openDownloadStream(file._id);
+
+	const g = gm(readable);
+
+	const stream = g
+		.resize(256, 256)
+		.compress('jpeg')
+		.quality(70)
+		.interlace('line')
+		.stream();
+
+	return stream;
+}
diff --git a/src/models/drive-file-thumbnail.ts b/src/models/drive-file-thumbnail.ts
new file mode 100644
index 0000000000..46de24379f
--- /dev/null
+++ b/src/models/drive-file-thumbnail.ts
@@ -0,0 +1,61 @@
+import * as mongo from 'mongodb';
+import monkDb, { nativeDbConn } from '../db/mongodb';
+
+const DriveFileThumbnail = monkDb.get<IDriveFileThumbnail>('driveFileThumbnails.files');
+DriveFileThumbnail.createIndex('metadata.originalId', { sparse: true, unique: true });
+export default DriveFileThumbnail;
+
+export const DriveFileThumbnailChunk = monkDb.get('driveFileThumbnails.chunks');
+
+export const getDriveFileThumbnailBucket = async (): Promise<mongo.GridFSBucket> => {
+	const db = await nativeDbConn();
+	const bucket = new mongo.GridFSBucket(db, {
+		bucketName: 'driveFileThumbnails'
+	});
+	return bucket;
+};
+
+export type IMetadata = {
+	originalId: mongo.ObjectID;
+};
+
+export type IDriveFileThumbnail = {
+	_id: mongo.ObjectID;
+	uploadDate: Date;
+	md5: string;
+	filename: string;
+	contentType: string;
+	metadata: IMetadata;
+};
+
+/**
+ * DriveFileThumbnailを物理削除します
+ */
+export async function deleteDriveFileThumbnail(driveFile: string | mongo.ObjectID | IDriveFileThumbnail) {
+	let d: IDriveFileThumbnail;
+
+	// Populate
+	if (mongo.ObjectID.prototype.isPrototypeOf(driveFile)) {
+		d = await DriveFileThumbnail.findOne({
+			_id: driveFile
+		});
+	} else if (typeof driveFile === 'string') {
+		d = await DriveFileThumbnail.findOne({
+			_id: new mongo.ObjectID(driveFile)
+		});
+	} else {
+		d = driveFile as IDriveFileThumbnail;
+	}
+
+	if (d == null) return;
+
+	// このDriveFileThumbnailのチャンクをすべて削除
+	await DriveFileThumbnailChunk.remove({
+		files_id: d._id
+	});
+
+	// このDriveFileThumbnailを削除
+	await DriveFileThumbnail.remove({
+		_id: d._id
+	});
+}
diff --git a/src/models/drive-file.ts b/src/models/drive-file.ts
index a8878d1197..2a7e95363a 100644
--- a/src/models/drive-file.ts
+++ b/src/models/drive-file.ts
@@ -6,6 +6,7 @@ import monkDb, { nativeDbConn } from '../db/mongodb';
 import Note, { deleteNote } from './note';
 import MessagingMessage, { deleteMessagingMessage } from './messaging-message';
 import User from './user';
+import DriveFileThumbnail, { deleteDriveFileThumbnail } from './drive-file-thumbnail';
 
 const DriveFile = monkDb.get<IDriveFile>('driveFiles.files');
 DriveFile.createIndex('metadata.uri', { sparse: true, unique: true });
@@ -13,7 +14,7 @@ export default DriveFile;
 
 export const DriveFileChunk = monkDb.get('driveFiles.chunks');
 
-const getGridFSBucket = async (): Promise<mongo.GridFSBucket> => {
+export const getDriveFileBucket = async (): Promise<mongo.GridFSBucket> => {
 	const db = await nativeDbConn();
 	const bucket = new mongo.GridFSBucket(db, {
 		bucketName: 'driveFiles'
@@ -21,8 +22,6 @@ const getGridFSBucket = async (): Promise<mongo.GridFSBucket> => {
 	return bucket;
 };
 
-export { getGridFSBucket };
-
 export type IMetadata = {
 	properties: any;
 	userId: mongo.ObjectID;
@@ -93,6 +92,11 @@ export async function deleteDriveFile(driveFile: string | mongo.ObjectID | IDriv
 		}
 	}
 
+	// このDriveFileのDriveFileThumbnailをすべて削除
+	await Promise.all((
+		await DriveFileThumbnail.find({ 'metadata.originalId': d._id })
+	).map(x => deleteDriveFileThumbnail(x)));
+
 	// このDriveFileのチャンクをすべて削除
 	await DriveFileChunk.remove({
 		files_id: d._id
diff --git a/src/server/file/index.ts b/src/server/file/index.ts
index 29056c63e7..973528da33 100644
--- a/src/server/file/index.ts
+++ b/src/server/file/index.ts
@@ -6,7 +6,6 @@ import * as fs from 'fs';
 import * as Koa from 'koa';
 import * as cors from '@koa/cors';
 import * as Router from 'koa-router';
-import pour from './pour';
 import sendDriveFile from './send-drive-file';
 
 // Init app
@@ -24,12 +23,14 @@ const router = new Router();
 
 router.get('/default-avatar.jpg', ctx => {
 	const file = fs.createReadStream(`${__dirname}/assets/avatar.jpg`);
-	pour(file, 'image/jpeg', ctx);
+	ctx.set('Content-Type', 'image/jpeg');
+	ctx.body = file;
 });
 
 router.get('/app-default.jpg', ctx => {
 	const file = fs.createReadStream(`${__dirname}/assets/dummy.png`);
-	pour(file, 'image/png', ctx);
+	ctx.set('Content-Type', 'image/jpeg');
+	ctx.body = file;
 });
 
 router.get('/:id', sendDriveFile);
diff --git a/src/server/file/pour.ts b/src/server/file/pour.ts
deleted file mode 100644
index 0fd0ad0e60..0000000000
--- a/src/server/file/pour.ts
+++ /dev/null
@@ -1,88 +0,0 @@
-import * as fs from 'fs';
-import * as stream from 'stream';
-import * as Koa from 'koa';
-import * as Gm from 'gm';
-
-const gm = Gm.subClass({
-	imageMagick: true
-});
-
-interface ISend {
-	contentType: string;
-	stream: stream.Readable;
-}
-
-function thumbnail(data: stream.Readable, type: string, resize: number): ISend {
-	const readable: stream.Readable = (() => {
-		// 動画であれば
-		if (/^video\/.*$/.test(type)) {
-			// TODO
-			// 使わないことになったストリームはしっかり取り壊す
-			data.destroy();
-			return fs.createReadStream(`${__dirname}/assets/thumbnail-not-available.png`);
-		// 画像であれば
-		// Note: SVGはapplication/xml
-		} else if (/^image\/.*$/.test(type) || type == 'application/xml') {
-			// 0フレーム目を送る
-			try {
-				return gm(data).selectFrame(0).stream();
-			// だめだったら
-			} catch (e) {
-				// 使わないことになったストリームはしっかり取り壊す
-				data.destroy();
-				return fs.createReadStream(`${__dirname}/assets/thumbnail-not-available.png`);
-			}
-		// 動画か画像以外
-		} else {
-			data.destroy();
-			return fs.createReadStream(`${__dirname}/assets/not-an-image.png`);
-		}
-	})();
-
-	let g = gm(readable);
-
-	if (resize) {
-		g = g.resize(resize, resize);
-	}
-
-	const stream = g
-		.compress('jpeg')
-		.quality(80)
-		.interlace('line')
-		.stream();
-
-	return {
-		contentType: 'image/jpeg',
-		stream
-	};
-}
-
-const commonReadableHandlerGenerator = (ctx: Koa.Context) => (e: Error): void => {
-	console.error(e);
-	ctx.status = 500;
-};
-
-export default function(readable: stream.Readable, type: string, ctx: Koa.Context): void {
-	readable.on('error', commonReadableHandlerGenerator(ctx));
-
-	const data = ((): ISend => {
-		if (ctx.query.thumbnail !== undefined) {
-			return thumbnail(readable, type, ctx.query.size);
-		}
-		return {
-			contentType: type,
-			stream: readable
-		};
-	})();
-
-	if (readable !== data.stream) {
-		data.stream.on('error', commonReadableHandlerGenerator(ctx));
-	}
-
-	if (ctx.query.download !== undefined) {
-		ctx.set('Content-Disposition', 'attachment');
-	}
-
-	ctx.set('Content-Type', data.contentType);
-	ctx.body = data.stream;
-}
diff --git a/src/server/file/send-drive-file.ts b/src/server/file/send-drive-file.ts
index ef458265a8..8719ddf70c 100644
--- a/src/server/file/send-drive-file.ts
+++ b/src/server/file/send-drive-file.ts
@@ -1,8 +1,15 @@
+import * as fs from 'fs';
+
 import * as Koa from 'koa';
 import * as send from 'koa-send';
 import * as mongodb from 'mongodb';
-import DriveFile, { getGridFSBucket } from '../../models/drive-file';
-import pour from './pour';
+import DriveFile, { getDriveFileBucket } from '../../models/drive-file';
+import DriveFileThumbnail, { getDriveFileThumbnailBucket } from '../../models/drive-file-thumbnail';
+
+const commonReadableHandlerGenerator = (ctx: Koa.Context) => (e: Error): void => {
+	console.error(e);
+	ctx.status = 500;
+};
 
 export default async function(ctx: Koa.Context) {
 	// Validate id
@@ -28,9 +35,33 @@ export default async function(ctx: Koa.Context) {
 		return;
 	}
 
-	const bucket = await getGridFSBucket();
+	if ('thumbnail' in ctx.query) {
+		// 動画か画像以外
+		if (!/^image\/.*$/.test(file.contentType) && !/^video\/.*$/.test(file.contentType)) {
+			const readable = fs.createReadStream(`${__dirname}/assets/thumbnail-not-available.png`);
+			ctx.set('Content-Type', 'image/png');
+			ctx.body = readable;
+		} else {
+			const thumb = await DriveFileThumbnail.findOne({ 'metadata.originalId': fileId });
+			if (thumb != null) {
+				ctx.set('Content-Type', 'image/jpeg');
+				const bucket = await getDriveFileThumbnailBucket();
+				ctx.body = bucket.openDownloadStream(thumb._id);
+			} else {
+				ctx.set('Content-Type', file.contentType);
+				const bucket = await getDriveFileBucket();
+				ctx.body = bucket.openDownloadStream(fileId);
+			}
+		}
+	} else {
+		if ('download' in ctx.query) {
+			ctx.set('Content-Disposition', 'attachment');
+		}
 
-	const readable = bucket.openDownloadStream(fileId);
-
-	pour(readable, file.contentType, ctx);
+		const bucket = await getDriveFileBucket();
+		const readable = bucket.openDownloadStream(fileId);
+		readable.on('error', commonReadableHandlerGenerator(ctx));
+		ctx.set('Content-Type', file.contentType);
+		ctx.body = readable;
+	}
 }
diff --git a/src/services/drive/add-file.ts b/src/services/drive/add-file.ts
index 279cdf0bc7..e7f3572c74 100644
--- a/src/services/drive/add-file.ts
+++ b/src/services/drive/add-file.ts
@@ -10,12 +10,14 @@ import * as debug from 'debug';
 import fileType = require('file-type');
 import prominence = require('prominence');
 
-import DriveFile, { IMetadata, getGridFSBucket, IDriveFile, DriveFileChunk } from '../../models/drive-file';
+import DriveFile, { IMetadata, getDriveFileBucket, IDriveFile, DriveFileChunk } from '../../models/drive-file';
 import DriveFolder from '../../models/drive-folder';
 import { pack } from '../../models/drive-file';
 import event, { publishDriveStream } from '../../publishers/stream';
 import getAcct from '../../acct/render';
 import { IUser, isLocalUser } from '../../models/user';
+import DriveFileThumbnail, { getDriveFileThumbnailBucket, DriveFileThumbnailChunk } from '../../models/drive-file-thumbnail';
+import genThumbnail from '../../drive/gen-thumbnail';
 
 const gm = _gm.subClass({
 	imageMagick: true
@@ -30,8 +32,8 @@ const tmpFile = (): Promise<[string, any]> => new Promise((resolve, reject) => {
 	});
 });
 
-const addToGridFS = (name: string, readable: stream.Readable, type: string, metadata: any): Promise<any> =>
-	getGridFSBucket()
+const writeChunks = (name: string, readable: stream.Readable, type: string, metadata: any) =>
+	getDriveFileBucket()
 		.then(bucket => new Promise((resolve, reject) => {
 			const writeStream = bucket.openUploadStream(name, { contentType: type, metadata });
 			writeStream.once('finish', resolve);
@@ -39,6 +41,20 @@ const addToGridFS = (name: string, readable: stream.Readable, type: string, meta
 			readable.pipe(writeStream);
 		}));
 
+const writeThumbnailChunks = (name: string, readable: stream.Readable, originalId) =>
+	getDriveFileThumbnailBucket()
+		.then(bucket => new Promise((resolve, reject) => {
+			const writeStream = bucket.openUploadStream(name, {
+				contentType: 'image/jpeg',
+				metadata: {
+					originalId
+				}
+			});
+			writeStream.once('finish', resolve);
+			writeStream.on('error', reject);
+			readable.pipe(writeStream);
+		}));
+
 const addFile = async (
 	user: IUser,
 	path: string,
@@ -232,6 +248,20 @@ const addFile = async (
 								'metadata.deletedAt': new Date()
 							}
 						});
+
+						//#region サムネイルもあれば削除
+						const thumbnail = await DriveFileThumbnail.findOne({
+							'metadata.originalId': oldFile._id
+						});
+
+						if (thumbnail) {
+							DriveFileThumbnailChunk.remove({
+								files_id: thumbnail._id
+							});
+
+							DriveFileThumbnail.remove({ _id: thumbnail._id });
+						}
+						//#endregion
 					}
 					//#endregion
 				}
@@ -263,7 +293,18 @@ const addFile = async (
 		metadata.uri = uri;
 	}
 
-	return addToGridFS(detectedName, readable, mime, metadata);
+	const file = await (writeChunks(detectedName, readable, mime, metadata) as Promise<IDriveFile>);
+
+	try {
+		const thumb = await genThumbnail(file);
+		if (thumb) {
+			await writeThumbnailChunks(detectedName, thumb, file._id);
+		}
+	} catch (e) {
+		// noop
+	}
+
+	return file;
 };
 
 /**