diff --git a/frontend/src/components/PostEditForm.tsx b/frontend/src/components/PostEditForm.tsx
index bb0e7d8..302c2d1 100644
--- a/frontend/src/components/PostEditForm.tsx
+++ b/frontend/src/components/PostEditForm.tsx
@@ -3,7 +3,6 @@ import { useEffect, useMemo, useState } from 'react'
 import { useLocale } from '@/lib/useLocale'
 import PostOriginalCreatedTimeField from '@/components/PostOriginalCreatedTimeField'
 import FieldError from '@/components/common/FieldError'
-import FieldWarning from '@/components/common/FieldWarning'
 import PostDurationField from '@/components/posts/PostDurationField'
 import PostTagsField from '@/components/posts/PostTagsField'
 import PostTextField from '@/components/posts/PostTextField'
@@ -154,6 +153,23 @@ const PostEditForm: FC<Props> = ({ post, onSave }) => {
     setDisabled (true)
     try
     {
+      const titleMissing = !title?.trim ()
+      const thumbnailMissing =
+	  !(post.thumbnail?.trim () || post.thumbnailBase?.trim ())
+
+      if ((titleMissing || thumbnailMissing)
+	  && !(await dialogue.confirm ({
+	      title: titleMissing
+		  ? label ('edit.titleMissingConfirmation')
+		  : label ('shared:labels.thumbnailMissing'),
+	      description: (titleMissing && thumbnailMissing)
+		  ? label ('shared:labels.thumbnailMissing')
+		  : undefined,
+	      confirmText: label ('shared:actions.update'),
+	      cancelText: label ('shared:actions.cancel'),
+	      closeLabel: label ('settings:actions.close') })))
+	return
+
       await update ({ id: post.id, title, tags, parentPostIds,
 		      duration: videoFlg ? duration : null,
 		      originalCreatedFrom, originalCreatedBefore },
@@ -173,9 +189,6 @@ const PostEditForm: FC<Props> = ({ post, onSave }) => {
   return (
       <form onSubmit={handleSubmit} className="max-w-xl pt-2 space-y-4">
 	<FieldError messages={baseErrors}/>
-	{!(post.thumbnail?.trim () || post.thumbnailBase?.trim ()) && (
-	    <FieldWarning
-		messages={[label ('shared:labels.thumbnailMissing')]}/>)}
 
 	<PostTextField
 	    label={label ('shared:labels.title')}
diff --git a/frontend/src/locales/ain-Kana/posts.json b/frontend/src/locales/ain-Kana/posts.json
index 0310a6b..9001c2f 100644
--- a/frontend/src/locales/ain-Kana/posts.json
+++ b/frontend/src/locales/ain-Kana/posts.json
@@ -1,4 +1,5 @@
 {
+  "_untranslated": ["edit.titleMissingConfirmation"],
   "list": {
     "tagline": "{{brand}}",
     "empty": "ミンタㇻ　タ　ネン　カ　イサㇺ",
@@ -31,6 +32,7 @@
     "showExternal": "ソイタㇰ　ソㇱ　アヌカレ"
   },
   "edit": {
+    "titleMissingConfirmation": "タイトルが設定されてゐません．更新しますか?",
     "validationFailed": "アシㇼ　カㇻ　カ　エアイカㇷ゚……",
     "conflictTitle": "モㇱマ　クㇽ　アシㇼ　カㇻ　ワ　アン！",
     "conflictDescription": "モㇱマ　イカㇻ　クㇽ　エエトコ　アシㇼ　カㇻ　ワ　アン。",
diff --git a/frontend/src/locales/ja/posts.json b/frontend/src/locales/ja/posts.json
index b6c1308..209d390 100644
--- a/frontend/src/locales/ja/posts.json
+++ b/frontend/src/locales/ja/posts.json
@@ -22,6 +22,7 @@
     "question": "表示しますか?", "showExternal": "外部ページを表示"
   },
   "edit": {
+    "titleMissingConfirmation": "タイトルが設定されてゐません．更新しますか?",
     "validationFailed": "更新はできなかったよ……",
     "conflictTitle": "競合が発生しました．",
     "conflictDescription": "ほかの耕作員が先に更新してゐます．",