diff --git a/CHANGELOG_CHERRYPICK.md b/CHANGELOG_CHERRYPICK.md
index fb5c7994ea..f44e4886fc 100644
--- a/CHANGELOG_CHERRYPICK.md
+++ b/CHANGELOG_CHERRYPICK.md
@@ -15,6 +15,7 @@
 - 클라이언트: (friendly) 모바일 환경에서 스크롤을 내리면 플로팅 버튼이 감춰지도록 변경
 - 클라이언트: (friendly) 서버와 연결이 끊어졌을 때 10초간 경고를 표시한 후 자동으로 숨기기
 - 클라이언트: (friendly) 서버와 연결이 끊어졌을 때 헤더에 연결 끊김 표시
+- 클라이언트: (friendly) 모바일 환경에서 노트 작성 폼의 디자인 개선
 - 클라이언트: Google Translate 서비스 추가 (thanks to @ltlapy)
 - 클라이언트: DeepL과 Google Translate를 선택할 수 있는 옵션 추가
 - 클라이언트: Enter 키를 눌러 보내기 옵션 추가
diff --git a/packages/client/src/components/post-form.vue b/packages/client/src/components/post-form.vue
index 038d06a75d..45baf38f79 100644
--- a/packages/client/src/components/post-form.vue
+++ b/packages/client/src/components/post-form.vue
@@ -1,7 +1,7 @@
 <template>
 <div
 	v-size="{ max: [310, 500] }" class="gafaadew"
-	:class="{ modal, _popup: modal, friendly: isFriendly }"
+	:class="{ modal, _popup: modal, friendly: isFriendly, 'friendly-not-desktop': isFriendly && !isDesktop }"
 	@dragover.stop="onDragover"
 	@dragenter="onDragenter"
 	@dragleave="onDragleave"
@@ -41,7 +41,7 @@
 		</div>
 		<MkInfo v-if="hasNotSpecifiedMentions" warn class="hasNotSpecifiedMentions">{{ i18n.ts.notSpecifiedMentionWarning }} - <button class="_textButton" @click="addMissingMention()">{{ i18n.ts.add }}</button></MkInfo>
 		<input v-show="useCw" ref="cwInputEl" v-model="cw" class="cw" :placeholder="i18n.ts.annotation" @keydown="onKeydown">
-		<textarea ref="textareaEl" v-model="text" class="text" :class="{ withCw: useCw }" :disabled="posting" :placeholder="placeholder" data-cy-post-form-text @keydown="onKeydown" @paste="onPaste" @compositionupdate="onCompositionUpdate" @compositionend="onCompositionEnd"/>
+		<textarea ref="textareaEl" v-model="text" class="text" :class="{ withCw: useCw, 'friendly-not-desktop': isFriendly && !isDesktop }" :disabled="posting" :placeholder="placeholder" data-cy-post-form-text @keydown="onKeydown" @paste="onPaste" @compositionupdate="onCompositionUpdate" @compositionend="onCompositionEnd"/>
 		<input v-show="withHashtags" ref="hashtagsInputEl" v-model="hashtags" class="hashtags" :placeholder="i18n.ts.hashtags" list="hashtags">
 		<XPostFormAttaches class="attaches" :files="files" @updated="updateFiles" @detach="detachFile" @changeSensitive="updateFileSensitive" @changeName="updateFileName"/>
 		<XPollEditor v-if="poll" v-model="poll" @destroyed="poll = null"/>
@@ -64,7 +64,7 @@
 </template>
 
 <script lang="ts" setup>
-import { inject, watch, nextTick, onMounted, defineAsyncComponent } from 'vue';
+import { inject, watch, nextTick, onMounted, defineAsyncComponent, ref } from 'vue';
 import * as mfm from 'mfm-js';
 import * as misskey from 'misskey-js';
 import insertTextAtCursor from 'insert-text-at-cursor';
@@ -90,8 +90,18 @@ import { i18n } from '@/i18n';
 import { instance } from '@/instance';
 import { $i, getAccounts, openAccountMenu as openAccountMenu_ } from '@/account';
 import { uploadFile } from '@/scripts/upload';
+import { deviceKind } from '@/scripts/device-kind';
 
 const isFriendly = $ref(localStorage.getItem('ui') === 'friendly');
+const DESKTOP_THRESHOLD = 1100;
+const MOBILE_THRESHOLD = 500;
+
+// デスクトップでウィンドウを狭くしたときモバイルUIが表示されて欲しいことはあるので deviceKind === 'desktop' の判定は行わない
+const isDesktop = ref(window.innerWidth >= DESKTOP_THRESHOLD);
+const isMobile = ref(deviceKind === 'smartphone' || window.innerWidth <= MOBILE_THRESHOLD);
+window.addEventListener('resize', () => {
+	isMobile.value = deviceKind === 'smartphone' || window.innerWidth <= MOBILE_THRESHOLD;
+});
 
 const modal = inject('modal');
 
@@ -720,6 +730,12 @@ onMounted(() => {
 
 		nextTick(() => watchForDraft());
 	});
+
+	if (!isDesktop.value) {
+		window.addEventListener('resize', () => {
+			if (window.innerWidth >= DESKTOP_THRESHOLD) isDesktop.value = true;
+		}, { passive: true });
+	}
 });
 </script>
 
@@ -736,6 +752,13 @@ onMounted(() => {
 		max-width: 800px;
 	}
 
+	&.friendly-not-desktop {
+		margin: initial !important;
+		padding: initial !important;
+		border-radius: initial !important;
+		max-width: 100% !important;
+	}
+
 	> header {
 		z-index: 1000;
 		height: 66px;
@@ -924,6 +947,10 @@ onMounted(() => {
 			&.withCw {
 				padding-top: 8px;
 			}
+
+			&.friendly-not-desktop {
+				min-height: 200px !important;
+			}
 		}
 
 		> footer {
@@ -984,6 +1011,10 @@ onMounted(() => {
 				min-height: 80px;
 			}
 
+			&.friendly-not-desktop {
+				min-height: 200px !important;
+			}
+
 			> footer {
 				padding: 0 8px 8px 8px;
 			}
diff --git a/packages/client/src/components/ui/modal.vue b/packages/client/src/components/ui/modal.vue
index 2305a02794..f7d589d8d8 100644
--- a/packages/client/src/components/ui/modal.vue
+++ b/packages/client/src/components/ui/modal.vue
@@ -2,7 +2,7 @@
 <transition :name="$store.state.animation ? (type === 'drawer') ? 'modal-drawer' : (type === 'popup') ? 'modal-popup' : 'modal' : ''" :duration="$store.state.animation ? 200 : 0" appear @after-leave="emit('closed')" @enter="emit('opening')" @after-enter="onOpened">
 	<div v-show="manualShowing != null ? manualShowing : showing" v-hotkey.global="keymap" class="qzhlnise" :class="{ drawer: type === 'drawer', dialog: type === 'dialog' || type === 'dialog:top', popup: type === 'popup' }" :style="{ zIndex, pointerEvents: (manualShowing != null ? manualShowing : showing) ? 'auto' : 'none', '--transformOrigin': transformOrigin }">
 		<div class="bg _modalBg" :class="{ transparent: transparentBg && (type === 'popup') }" :style="{ zIndex }" @click="onBgClick" @contextmenu.prevent.stop="() => {}"></div>
-		<div ref="content" class="content" :class="{ fixed, top: type === 'dialog:top' }" :style="{ zIndex }" @click.self="onBgClick">
+		<div ref="content" class="content" :class="{ fixed, top: type === 'dialog:top', friendly: isFriendly && !isDesktop }" :style="{ zIndex }" @click.self="onBgClick">
 			<slot :max-height="maxHeight" :type="type"></slot>
 		</div>
 	</div>
@@ -10,12 +10,23 @@
 </template>
 
 <script lang="ts" setup>
-import { nextTick, onMounted, watch, provide } from 'vue';
+import { nextTick, onMounted, watch, provide, ref } from 'vue';
 import * as os from '@/os';
 import { isTouchUsing } from '@/scripts/touch';
 import { defaultStore } from '@/store';
 import { deviceKind } from '@/scripts/device-kind';
 
+const isFriendly = $ref(localStorage.getItem('ui') === 'friendly');
+const DESKTOP_THRESHOLD = 1100;
+const MOBILE_THRESHOLD = 500;
+
+// デスクトップでウィンドウを狭くしたときモバイルUIが表示されて欲しいことはあるので deviceKind === 'desktop' の判定は行わない
+const isDesktop = ref(window.innerWidth >= DESKTOP_THRESHOLD);
+const isMobile = ref(deviceKind === 'smartphone' || window.innerWidth <= MOBILE_THRESHOLD);
+window.addEventListener('resize', () => {
+	isMobile.value = deviceKind === 'smartphone' || window.innerWidth <= MOBILE_THRESHOLD;
+});
+
 function getFixedContainer(el: Element | null): Element | null {
 	if (el == null || el.tagName === 'BODY') return null;
 	const position = window.getComputedStyle(el).getPropertyValue('position');
@@ -246,6 +257,12 @@ onMounted(() => {
 			align();
 		}).observe(content!);
 	});
+
+	if (!isDesktop.value) {
+		window.addEventListener('resize', () => {
+			if (window.innerWidth >= DESKTOP_THRESHOLD) isDesktop.value = true;
+		}, { passive: true });
+	}
 });
 
 defineExpose({
@@ -368,6 +385,11 @@ defineExpose({
 					margin-top: 0;
 				}
 			}
+
+			&.friendly {
+				padding: initial;
+				mask-image: initial;
+			}
 		}
 	}