diff --git a/packages/frontend/src/components/grid/MkDataCell.vue b/packages/frontend/src/components/grid/MkDataCell.vue
index 0e9eb5d15f..1c5690a04f 100644
--- a/packages/frontend/src/components/grid/MkDataCell.vue
+++ b/packages/frontend/src/components/grid/MkDataCell.vue
@@ -269,7 +269,7 @@ useTooltip(rootEl, (showing) => {
 		return;
 	}
 
-	const content = cell.value.violation.violations.map(it => it.result.message).join('\n');
+	const content = cell.value.violation.violations.filter(it => !it.valid).map(it => it.result.message).join('\n');
 	os.popup(defineAsyncComponent(() => import('@/components/grid/MkCellTooltip.vue')), {
 		showing,
 		content,
diff --git a/packages/frontend/src/components/grid/MkGrid.vue b/packages/frontend/src/components/grid/MkGrid.vue
index fd6339d244..f1b50d47c3 100644
--- a/packages/frontend/src/components/grid/MkGrid.vue
+++ b/packages/frontend/src/components/grid/MkGrid.vue
@@ -76,12 +76,14 @@ const props = defineProps<{
 }>();
 
 // non-reactive
+// eslint-disable-next-line vue/no-setup-props-destructure
 const rowSetting: Required<GridRowSetting> = {
 	...defaultGridRowSetting,
 	...props.settings.row,
 };
 
 // non-reactive
+// eslint-disable-next-line vue/no-setup-props-destructure
 const columnSettings = props.settings.cols;
 
 // non-reactive
@@ -1117,21 +1119,22 @@ function refreshData() {
 	// 行・列の定義から、元データの配列より値を取得してセルを作成する。
 	// 行・列の定義はそれぞれインデックスを持っており、そのインデックスは元データの配列番地に対応している。
 	const _cells: RowHolder[] = _rows.map(row => {
-		const cells = row.using
-			? _cols.map(col => {
-				const cell = createCell(col, row, _data[row.index][col.setting.bindTo], cellSettings);
-				cell.violation = cellValidation(cell, cell.value);
-				return cell;
-			})
+		const newCells = row.using
+			? _cols.map(col => createCell(col, row, _data[row.index][col.setting.bindTo], cellSettings))
 			: _cols.map(col => createCell(col, row, undefined, cellSettings));
 
-		return { row, cells, origin: _data[row.index] };
+		return { row, cells: newCells, origin: _data[row.index] };
 	});
 
 	rows.value = _rows;
 	cells.value = _cells;
 
-	applyRowRules(_cells.filter(it => it.row.using).flatMap(it => it.cells));
+	const allCells = _cells.filter(it => it.row.using).flatMap(it => it.cells);
+	for (const cell of allCells) {
+		cell.violation = cellValidation(allCells, cell, cell.value);
+	}
+
+	applyRowRules(allCells);
 
 	if (_DEV_) {
 		console.log('[grid][refresh-data][end]');
@@ -1205,7 +1208,6 @@ function patchData(newItems: DataSource[]) {
 			const oldCell = oldCells[colIdx];
 			const newValue = newItem[_col.setting.bindTo];
 			if (oldCell.value !== newValue) {
-				oldCell.violation = cellValidation(oldCell, newValue);
 				oldCell.value = _col.setting.valueTransformer
 					? _col.setting.valueTransformer(holder.row, _col, newValue)
 					: newValue;
@@ -1215,6 +1217,11 @@ function patchData(newItems: DataSource[]) {
 	}
 
 	if (changedCells.length > 0) {
+		const allCells = cells.value.slice(0, newItems.length).flatMap(it => it.cells);
+		for (const cell of allCells) {
+			cell.violation = cellValidation(allCells, cell, cell.value);
+		}
+
 		applyRowRules(changedCells);
 
 		// セル値が書き換わっており、バリデーションの結果も変わっているので外部に通知する必要がある
diff --git a/packages/frontend/src/components/grid/cell-validators.ts b/packages/frontend/src/components/grid/cell-validators.ts
index 7b2346b299..bccc923da1 100644
--- a/packages/frontend/src/components/grid/cell-validators.ts
+++ b/packages/frontend/src/components/grid/cell-validators.ts
@@ -6,6 +6,7 @@ export type ValidatorParams = {
 	column: GridColumn;
 	row: GridRow;
 	value: CellValue;
+	allCells: GridCell[];
 };
 
 export type ValidatorResult = {
@@ -13,7 +14,7 @@ export type ValidatorResult = {
 	message?: string;
 }
 
-export type CellValidator = {
+export type GridCellValidator = {
 	name?: string;
 	ignoreViolation?: boolean;
 	validate: (params: ValidatorParams) => ValidatorResult;
@@ -27,11 +28,11 @@ export type ValidateViolation = {
 
 export type ValidateViolationItem = {
 	valid: boolean;
-	validator: CellValidator;
+	validator: GridCellValidator;
 	result: ValidatorResult;
 }
 
-export function cellValidation(cell: GridCell, newValue: CellValue): ValidateViolation {
+export function cellValidation(allCells: GridCell[], cell: GridCell, newValue: CellValue): ValidateViolation {
 	const { column, row } = cell;
 	const validators = column.setting.validators ?? [];
 
@@ -39,6 +40,7 @@ export function cellValidation(cell: GridCell, newValue: CellValue): ValidateVio
 		column,
 		row,
 		value: newValue,
+		allCells,
 	};
 
 	const violations: ValidateViolationItem[] = validators.map(validator => {
@@ -58,11 +60,10 @@ export function cellValidation(cell: GridCell, newValue: CellValue): ValidateVio
 }
 
 class ValidatorPreset {
-	required(): CellValidator {
+	required(): GridCellValidator {
 		return {
 			name: 'required',
-			validate: (params: ValidatorParams): ValidatorResult => {
-				const { value } = params;
+			validate: ({ value }): ValidatorResult => {
 				return {
 					valid: value !== null && value !== undefined && value !== '',
 					message: 'This field is required.',
@@ -71,11 +72,10 @@ class ValidatorPreset {
 		};
 	}
 
-	regex(pattern: RegExp): CellValidator {
+	regex(pattern: RegExp): GridCellValidator {
 		return {
 			name: 'regex',
-			validate: (params: ValidatorParams): ValidatorResult => {
-				const { value, column } = params;
+			validate: ({ value, column }): ValidatorResult => {
 				if (column.setting.type !== 'text') {
 					return {
 						valid: false,
@@ -90,6 +90,22 @@ class ValidatorPreset {
 			},
 		};
 	}
+
+	unique(): GridCellValidator {
+		return {
+			name: 'unique',
+			validate: ({ column, row, value, allCells }): ValidatorResult => {
+				const bindTo = column.setting.bindTo;
+				const isUnique = allCells
+					.filter(it => it.column.setting.bindTo === bindTo && it.row.index !== row.index)
+					.every(cell => cell.value !== value);
+				return {
+					valid: isUnique,
+					message: 'This value is already used.',
+				};
+			},
+		};
+	}
 }
 
 export const validators = new ValidatorPreset();
diff --git a/packages/frontend/src/components/grid/column.ts b/packages/frontend/src/components/grid/column.ts
index 5e189224c1..360cf77fe3 100644
--- a/packages/frontend/src/components/grid/column.ts
+++ b/packages/frontend/src/components/grid/column.ts
@@ -1,4 +1,4 @@
-import { CellValidator } from '@/components/grid/cell-validators.js';
+import { GridCellValidator } from '@/components/grid/cell-validators.js';
 import { Size, SizeStyle } from '@/components/grid/grid.js';
 import { calcCellWidth } from '@/components/grid/grid-utils.js';
 import { CellValue, GridCell } from '@/components/grid/cell.js';
@@ -19,7 +19,7 @@ export type GridColumnSetting = {
 	type: ColumnType;
 	width: SizeStyle;
 	editable?: boolean;
-	validators?: CellValidator[];
+	validators?: GridCellValidator[];
 	customValueEditor?: CustomValueEditor;
 	valueTransformer?: CellValueTransformer;
 	contextMenuFactory?: GridColumnContextMenuFactory;
diff --git a/packages/frontend/src/pages/admin/custom-emojis-manager.impl.ts b/packages/frontend/src/pages/admin/custom-emojis-manager.impl.ts
index b5c70295c0..900217c683 100644
--- a/packages/frontend/src/pages/admin/custom-emojis-manager.impl.ts
+++ b/packages/frontend/src/pages/admin/custom-emojis-manager.impl.ts
@@ -17,3 +17,20 @@ export function emptyStrToEmptyArray(value: string) {
 	return value === '' ? [] : value.split(',').map(it => it.trim());
 }
 
+export function roleIdsParser(text: string): { id: string, name: string }[] {
+	// idとnameのペア配列をJSONで受け取る。それ以外の形式は許容しない
+	try {
+		const obj = JSON.parse(text);
+		if (!Array.isArray(obj)) {
+			return [];
+		}
+		if (!obj.every(it => typeof it === 'object' && 'id' in it && 'name' in it)) {
+			return [];
+		}
+
+		return obj.map(it => ({ id: it.id, name: it.name }));
+	} catch (ex) {
+		console.warn(ex);
+		return [];
+	}
+}
diff --git a/packages/frontend/src/pages/admin/custom-emojis-manager.local.list.vue b/packages/frontend/src/pages/admin/custom-emojis-manager.local.list.vue
index e4f43804fa..d3565354d1 100644
--- a/packages/frontend/src/pages/admin/custom-emojis-manager.local.list.vue
+++ b/packages/frontend/src/pages/admin/custom-emojis-manager.local.list.vue
@@ -189,13 +189,13 @@ import {
 	emptyStrToEmptyArray,
 	emptyStrToNull,
 	emptyStrToUndefined,
-	RequestLogItem,
+	RequestLogItem, roleIdsParser,
 } from '@/pages/admin/custom-emojis-manager.impl.js';
 import MkGrid from '@/components/grid/MkGrid.vue';
 import { i18n } from '@/i18n.js';
 import MkInput from '@/components/MkInput.vue';
 import MkButton from '@/components/MkButton.vue';
-import { validators } from '@/components/grid/cell-validators.js';
+import { GridCellValidator, validators } from '@/components/grid/cell-validators.js';
 import { GridCellValidationEvent, GridCellValueChangeEvent, GridEvent } from '@/components/grid/grid-event.js';
 import { misskeyApi } from '@/scripts/misskey-api.js';
 import MkPagingButtons from '@/components/MkPagingButtons.vue';
@@ -247,6 +247,7 @@ type GridSortOrder = {
 function setupGrid(): GridSetting {
 	const required = validators.required();
 	const regex = validators.regex(/^[a-zA-Z0-9_]+$/);
+	const unique = validators.unique();
 	return {
 		row: {
 			showNumber: true,
@@ -302,7 +303,10 @@ function setupGrid(): GridSetting {
 					return file.url;
 				},
 			},
-			{ bindTo: 'name', title: 'name', type: 'text', editable: true, width: 140, validators: [required, regex] },
+			{
+				bindTo: 'name', title: 'name', type: 'text', editable: true, width: 140,
+				validators: [required, regex, unique],
+			},
 			{ bindTo: 'category', title: 'category', type: 'text', editable: true, width: 140 },
 			{ bindTo: 'aliases', title: 'aliases', type: 'text', editable: true, width: 140 },
 			{ bindTo: 'license', title: 'license', type: 'text', editable: true, width: 140 },
@@ -335,23 +339,7 @@ function setupGrid(): GridSetting {
 					return transform;
 				},
 				events: {
-					paste(text) {
-						// idとnameのペア配列をJSONで受け取る。それ以外の形式は許容しない
-						try {
-							const obj = JSON.parse(text);
-							if (!Array.isArray(obj)) {
-								return [];
-							}
-							if (!obj.every(it => typeof it === 'object' && 'id' in it && 'name' in it)) {
-								return [];
-							}
-
-							return obj.map(it => ({ id: it.id, name: it.name }));
-						} catch (ex) {
-							console.warn(ex);
-							return [];
-						}
-					},
+					paste: roleIdsParser,
 					delete(cell) {
 						// デフォルトはundefinedになるが、このプロパティは空配列にしたい
 						gridItems.value[cell.row.index].roleIdsThatCanBeUsedThisEmojiAsReaction = [];
diff --git a/packages/frontend/src/pages/admin/custom-emojis-manager.local.register.vue b/packages/frontend/src/pages/admin/custom-emojis-manager.local.register.vue
index 2511ccbc66..bea0618a07 100644
--- a/packages/frontend/src/pages/admin/custom-emojis-manager.local.register.vue
+++ b/packages/frontend/src/pages/admin/custom-emojis-manager.local.register.vue
@@ -75,7 +75,12 @@
 import * as Misskey from 'misskey-js';
 import { onMounted, ref } from 'vue';
 import { misskeyApi } from '@/scripts/misskey-api.js';
-import { emptyStrToEmptyArray, emptyStrToNull, RequestLogItem } from '@/pages/admin/custom-emojis-manager.impl.js';
+import {
+	emptyStrToEmptyArray,
+	emptyStrToNull,
+	RequestLogItem,
+	roleIdsParser,
+} from '@/pages/admin/custom-emojis-manager.impl.js';
 import MkGrid from '@/components/grid/MkGrid.vue';
 import { i18n } from '@/i18n.js';
 import MkSelect from '@/components/MkSelect.vue';
@@ -117,6 +122,7 @@ type GridItem = {
 function setupGrid(): GridSetting {
 	const required = validators.required();
 	const regex = validators.regex(/^[a-zA-Z0-9_]+$/);
+	const unique = validators.unique();
 
 	function removeRows(rows: GridRow[]) {
 		const idxes = [...new Set(rows.map(it => it.index))];
@@ -158,7 +164,10 @@ function setupGrid(): GridSetting {
 		},
 		cols: [
 			{ bindTo: 'url', icon: 'ti-icons', type: 'image', editable: false, width: 'auto', validators: [required] },
-			{ bindTo: 'name', title: 'name', type: 'text', editable: true, width: 140, validators: [required, regex] },
+			{
+				bindTo: 'name', title: 'name', type: 'text', editable: true, width: 140,
+				validators: [required, regex, unique],
+			},
 			{ bindTo: 'category', title: 'category', type: 'text', editable: true, width: 140 },
 			{ bindTo: 'aliases', title: 'aliases', type: 'text', editable: true, width: 140 },
 			{ bindTo: 'license', title: 'license', type: 'text', editable: true, width: 140 },
@@ -190,6 +199,13 @@ function setupGrid(): GridSetting {
 
 					return transform;
 				},
+				events: {
+					paste: roleIdsParser,
+					delete(cell) {
+						// デフォルトはundefinedになるが、このプロパティは空配列にしたい
+						gridItems.value[cell.row.index].roleIdsThatCanBeUsedThisEmojiAsReaction = [];
+					},
+				},
 			},
 		],
 		cells: {
@@ -343,16 +359,14 @@ async function onDrop(ev: DragEvent) {
 }
 
 async function onFileSelectClicked() {
-	const driveFiles = await os.promiseDialog(
-		chooseFileFromPc(
-			true,
-			{
-				uploadFolder: selectedFolderId.value,
-				keepOriginal: keepOriginalUploading.value,
-				// 拡張子は消す
-				nameConverter: (file) => file.name.replace(/\.[a-zA-Z0-9]+$/, ''),
-			},
-		),
+	const driveFiles = await chooseFileFromPc(
+		true,
+		{
+			uploadFolder: selectedFolderId.value,
+			keepOriginal: keepOriginalUploading.value,
+			// 拡張子は消す
+			nameConverter: (file) => file.name.replace(/\.[a-zA-Z0-9]+$/, ''),
+		},
 	);
 
 	gridItems.value.push(...driveFiles.map(fromDriveFile));
diff --git a/packages/frontend/src/pages/admin/custom-emojis-manager2.stories.impl.ts b/packages/frontend/src/pages/admin/custom-emojis-manager2.stories.impl.ts
index c4c5a66241..373f1d3211 100644
--- a/packages/frontend/src/pages/admin/custom-emojis-manager2.stories.impl.ts
+++ b/packages/frontend/src/pages/admin/custom-emojis-manager2.stories.impl.ts
@@ -118,18 +118,18 @@ function createRender(params: {
 						const body = await new Response(bodyStream).json() as entities.AdminEmojiAddRequest;
 
 						const fileId = body.fileId;
-						const file = storedDriveFiles.find(f => f.id === fileId);
+						// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+						const file = storedDriveFiles.find(f => f.id === fileId)!;
 
 						const em = emoji({
 							id: fakeId(),
 							name: body.name,
-							url: body.url,
 							publicUrl: file.url,
 							originalUrl: file.url,
 							type: file.type,
 							aliases: body.aliases,
-							category: body.category,
-							license: body.license,
+							category: body.category ?? undefined,
+							license: body.license ?? undefined,
 							localOnly: body.localOnly,
 							isSensitive: body.isSensitive,
 						});