diff --git a/src/mfm/parser.ts b/src/mfm/parser.ts
index 3edb23b602..480d590755 100644
--- a/src/mfm/parser.ts
+++ b/src/mfm/parser.ts
@@ -112,9 +112,27 @@ const mfm = P.createLanguage({
 			const text = input.substr(i);
 			const match = text.match(/^#([^\s\.,!\?#]+)/i);
 			if (!match) return P.makeFailure(i, 'not a hashtag');
-			if (match[1].match(/^[0-9]+$/)) return P.makeFailure(i, 'not a hashtag');
-			if (input[i - 1] != '\n' && input[i - 1] != ' ' && input[i - 1] != null) return P.makeFailure(i, 'require space before "#"');
-			return P.makeSuccess(i + match[0].length, makeNode('hashtag', { hashtag: match[1] }));
+			let hashtag = match[1];
+			let pendingBracket = 0;
+			const end = hashtag.split('').findIndex(char => {
+				if (char == ')') {
+					if (pendingBracket > 0) {
+						pendingBracket--;
+						return false;
+					} else {
+						return true;
+					}
+				} else if (char == '(') {
+					pendingBracket++;
+					return false;
+				} else {
+					return false;
+				}
+			});
+			if (end > 0) hashtag = hashtag.substr(0, end);
+			if (hashtag.match(/^[0-9]+$/)) return P.makeFailure(i, 'not a hashtag');
+			if (!['\n', ' ', '(', null, undefined].includes(input[i - 1])) return P.makeFailure(i, 'require space before "#"');
+			return P.makeSuccess(i + ('#' + hashtag).length, makeNode('hashtag', { hashtag: hashtag }));
 		}),
 	//#endregion
 
diff --git a/test/mfm.ts b/test/mfm.ts
index 206105bc56..9956f679bf 100644
--- a/test/mfm.ts
+++ b/test/mfm.ts
@@ -212,12 +212,37 @@ describe('Text', () => {
 				], tokens);
 			});
 
+			it('with brackets', () => {
+				const tokens = analyze('(#foo)');
+				assert.deepEqual([
+					text('('),
+					node('hashtag', { hashtag: 'foo' }),
+					text(')'),
+				], tokens);
+			});
+
+			it('with brackets (space before)', () => {
+				const tokens = analyze('(bar #foo)');
+				assert.deepEqual([
+					text('(bar '),
+					node('hashtag', { hashtag: 'foo' }),
+					text(')'),
+				], tokens);
+			});
+
 			it('disallow number only', () => {
 				const tokens = analyze('#123');
 				assert.deepEqual([
 					text('#123'),
 				], tokens);
 			});
+
+			it('disallow number only (with brackets)', () => {
+				const tokens = analyze('(#123)');
+				assert.deepEqual([
+					text('(#123)'),
+				], tokens);
+			});
 		});
 
 		describe('quote', () => {