diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index e2cf11b49..a14e5e819 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -222,6 +222,7 @@ currentPassword: "現在のパスワード"
 newPassword: "新しいパスワード"
 newPasswordRetype: "新しいパスワード(再入力)"
 attachFile: "ファイルを添付"
+attachVideoFile: "MOVファイルを添付"
 more: "もっと！"
 featured: "ハイライト"
 usernameOrUserId: "ユーザー名かユーザーID"
diff --git a/locales/ja-NY.yml b/locales/ja-NY.yml
index d9f16b961..546270ad8 100644
--- a/locales/ja-NY.yml
+++ b/locales/ja-NY.yml
@@ -221,6 +221,7 @@ currentPassword: "現在のパスワード"
 newPassword: "新しいパスワード"
 newPasswordRetype: "新しいパスワード(再入力)"
 attachFile: "ファイルを添付"
+attachVideoFile: "MOVファイルを添付"
 more: "もっと！"
 featured: "ハイライト"
 usernameOrUserId: "ユーザー名かユーザーID"
diff --git a/packages/client/src/components/post-form.vue b/packages/client/src/components/post-form.vue
index 656689ddc..8e1633204 100644
--- a/packages/client/src/components/post-form.vue
+++ b/packages/client/src/components/post-form.vue
@@ -47,6 +47,7 @@
 		<XNotePreview v-if="showPreview" class="preview" :text="text"/>
 		<footer>
 			<button v-tooltip="i18n.ts.attachFile" class="_button" @click="chooseFileFrom"><i class="fas fa-photo-video"></i></button>
+			<button v-tooltip="i18n.ts.attachVideoFile" class="_button" @click="chooseFileFromEnc"><i class="far fa-file-video"></i></button>
 			<button v-tooltip="i18n.ts.poll" class="_button" :class="{ active: poll }" @click="togglePoll"><i class="fas fa-poll-h"></i></button>
 			<button v-tooltip="i18n.ts.useCw" class="_button" :class="{ active: useCw }" @click="useCw = !useCw"><i class="fas fa-eye-slash"></i></button>
 			<button v-tooltip="i18n.ts.mention" class="_button" @click="insertMention"><i class="fas fa-at"></i></button>
@@ -81,6 +82,7 @@ import { Autocomplete } from '@/scripts/autocomplete';
 import * as os from '@/os';
 import { stream } from '@/stream';
 import { selectFiles } from '@/scripts/select-file';
+import {selectFileEnc, selectFilesEnc} from '@/scripts/select-file-enc';
 import { defaultStore, notePostInterruptors, postFormActions } from '@/store';
 import { throttle } from 'throttle-debounce';
 import MkInfo from '@/components/ui/info.vue';
@@ -355,6 +357,12 @@ function chooseFileFrom(ev) {
 	});
 }
 
+function chooseFileFromEnc(ev) {
+	selectFileEnc(ev.currentTarget ?? ev.target, i18n.ts.attachVideoFile).then(files_ => {
+		files.push(files_);
+	});
+}
+
 function detachFile(id) {
 	files = files.filter(x => x.id != id);
 }
diff --git a/packages/client/src/scripts/select-file-enc.ts b/packages/client/src/scripts/select-file-enc.ts
new file mode 100644
index 000000000..eae57aa00
--- /dev/null
+++ b/packages/client/src/scripts/select-file-enc.ts
@@ -0,0 +1,155 @@
+import { ref } from 'vue';
+import * as os from '@/os';
+import { stream } from '@/stream';
+import { i18n } from '@/i18n';
+import { defaultStore } from '@/store';
+import { DriveFile } from 'misskey-js/built/entities';
+
+function select(src: any, label: string | null, multiple: boolean): Promise<DriveFile | DriveFile[]> {
+	return new Promise((res, rej) => {
+		const keepOriginal = ref(defaultStore.state.keepOriginalUploading);
+
+		const chooseFileFromPc = () => {
+			const input = document.createElement('input');
+			input.type = 'file';
+			input.multiple = multiple;
+			input.onchange = () => {
+
+				//ここから
+				// @ts-ignore
+				function VideoConverter (videoFileData, targetFormat) {
+					try {
+						targetFormat = targetFormat.toLowerCase();
+						let reader = new FileReader();
+						return new Promise(resolve => {
+							reader.onload = function (event) {
+								let contentType = 'video/'+targetFormat;
+
+								// @ts-ignore
+								let fileData: ArrayBuffer = event.target.result.split(',');
+								let b64Data = fileData[1];
+								let blob = getBlobFromBase64Data(b64Data, contentType);
+								let blobUrl = URL.createObjectURL(blob);
+
+								let convertedVideo: any = {
+									name: videoFileData.name.substring(0, videoFileData.name.lastIndexOf(".")),
+									format: targetFormat,
+									data: blob
+								}
+								// console.log("convertedVideo: ", convertedVideo);
+								resolve(convertedVideo);
+							}
+							reader.readAsDataURL(videoFileData);
+						});
+
+					} catch (e) {
+						console.log("Error occurred while converting : ", e);
+					}
+				}
+
+				function getBlobFromBase64Data(b64Data, contentType, sliceSize=512) {
+					const byteCharacters = atob(b64Data);
+					const byteArrays = [];
+
+					for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) {
+						const slice = byteCharacters.slice(offset, offset + sliceSize);
+
+						const byteNumbers = new Array(slice.length);
+						for (let i = 0; i < slice.length; i++) {
+							byteNumbers[i] = slice.charCodeAt(i);
+						}
+
+						const byteArray = new Uint8Array(byteNumbers);
+						// @ts-ignore
+						byteArrays.push(byteArray);
+					}
+
+					const blob = new Blob(byteArrays, {type: contentType});
+					return blob;
+				}
+
+				//ここまで
+
+				/*
+				MIT License
+
+				Copyright (c) 2021 Suvro Debnath
+
+				Permission is hereby granted, free of charge, to any person obtaining a copy
+				of this software and associated documentation files (the "Software"), to deal
+				in the Software without restriction, including without limitation the rights
+				to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+				copies of the Software, and to permit persons to whom the Software is
+				furnished to do so, subject to the following conditions:
+
+				The above copyright notice and this permission notice shall be included in all
+				copies or substantial portions of the Software.
+
+				THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+				IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+				FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+				AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+				LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+				OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+				SOFTWARE.
+				 */
+
+
+				Array.from(input.files).map(async file => {
+					if (file.type.indexOf('video') == -1) {
+						os.toast('It is not video file');
+						return
+					}
+
+					console.log('convert video');
+					os.toast('Try convert to mp4');
+					//convertVideo(file);
+					let sourceVideoFile = file;
+					let targetVideoFormat = 'mp4'
+					console.log('start convert video');
+					let convertedVideoDataObj = await VideoConverter(sourceVideoFile, targetVideoFormat);
+					console.log('end convert video');
+
+					// @ts-ignore
+					let convertedVideoFile = new File([convertedVideoDataObj.data], convertedVideoDataObj.name + "." + convertedVideoDataObj.format);
+
+					os.upload(convertedVideoFile, defaultStore.state.uploadFolder).then(driveFiles => {
+						res(driveFiles);
+					}).catch(e => {
+						os.alert({
+							type: 'error',
+							text: e
+						});
+					});
+				});
+
+
+				// 一応廃棄
+				(window as any).__misskey_input_ref__ = null;
+			};
+
+			// https://qiita.com/fukasawah/items/b9dc732d95d99551013d
+			// iOS Safari で正常に動かす為のおまじない
+			(window as any).__misskey_input_ref__ = input;
+
+			input.click();
+		};
+
+		os.popupMenu([label ? {
+			text: label,
+			type: 'label'
+		} : undefined, {
+			text: i18n.ts.upload,
+			icon: 'fas fa-upload',
+			action: chooseFileFromPc
+		}], src);
+	});
+}
+
+export function selectFileEnc(src: any, label: string | null = null): Promise<DriveFile> {
+	return select(src, label, false) as Promise<DriveFile>;
+}
+
+export function selectFilesEnc(src: any, label: string | null = null): Promise<DriveFile[]> {
+	return select(src, label, true) as Promise<DriveFile[]>;
+}
diff --git a/packages/client/src/scripts/select-file.ts b/packages/client/src/scripts/select-file.ts
index 23df4edf5..2c26fd6ca 100644
--- a/packages/client/src/scripts/select-file.ts
+++ b/packages/client/src/scripts/select-file.ts
@@ -5,6 +5,7 @@ import { i18n } from '@/i18n';
 import { defaultStore } from '@/store';
 import { DriveFile } from 'misskey-js/built/entities';
 
+
 function select(src: any, label: string | null, multiple: boolean): Promise<DriveFile | DriveFile[]> {
 	return new Promise((res, rej) => {
 		const keepOriginal = ref(defaultStore.state.keepOriginalUploading);