diff --git a/packages/frontend/src/components/global/MkMisskeyFlavoredMarkdown.ts b/packages/frontend/src/components/global/MkMisskeyFlavoredMarkdown.ts
index 0bcd0d23f..1822996b4 100644
--- a/packages/frontend/src/components/global/MkMisskeyFlavoredMarkdown.ts
+++ b/packages/frontend/src/components/global/MkMisskeyFlavoredMarkdown.ts
@@ -294,6 +294,20 @@ export default function (props: MfmProps, { emit }: { emit: SetupContext<MfmEven
 						style = `background-color: #${color}; overflow-wrap: anywhere;`;
 						break;
 					}
+					case 'small': {
+						return h(
+							"small",
+							{
+								style: "opacity: 0.7;",
+							}, genEl(token.children));
+					}
+					case 'center': {
+						return h(
+							"div",
+							{
+								style: "text-align: center;",
+							}, genEl(token.children));
+					}
 					case 'border': {
 						let color = validColor(token.props.args.color);
 						color = color ? `#${color}` : 'var(--accent)';
diff --git a/packages/frontend/src/const.ts b/packages/frontend/src/const.ts
index 3f7ba0800..67af428a2 100644
--- a/packages/frontend/src/const.ts
+++ b/packages/frontend/src/const.ts
@@ -122,7 +122,7 @@ export const DEFAULT_SERVER_ERROR_IMAGE_URL = 'https://xn--931a.moe/assets/error
 export const DEFAULT_NOT_FOUND_IMAGE_URL = 'https://xn--931a.moe/assets/not-found.jpg';
 export const DEFAULT_INFO_IMAGE_URL = 'https://xn--931a.moe/assets/info.jpg';
 
-export const MFM_TAGS = ['tada', 'jelly', 'twitch', 'shake', 'spin', 'jump', 'bounce', 'flip', 'x2', 'x3', 'x4', 'scale', 'position', 'fg', 'bg', 'border', 'font', 'blur', 'rainbow', 'sparkle', 'rotate', 'ruby', 'unixtime', 'crop', 'fade'];
+export const MFM_TAGS = ['tada', 'jelly', 'twitch', 'shake', 'spin', 'jump', 'bounce', 'flip', 'x2', 'x3', 'x4', 'scale', 'position', 'fg', 'bg', 'border', 'font', 'blur', 'rainbow', 'sparkle', 'rotate', 'ruby', 'unixtime', 'crop', 'fade', 'center', 'small'];
 export const MFM_PARAMS: Record<typeof MFM_TAGS[number], string[]> = {
 	tada: ['speed=', 'delay='],
 	jelly: ['speed=', 'delay='],
@@ -148,4 +148,6 @@ export const MFM_PARAMS: Record<typeof MFM_TAGS[number], string[]> = {
 	unixtime: [],
 	fade: ['speed=', 'delay=', 'loop=', 'out'],
 	crop: ['top=', 'bottom=', 'left=', 'right='],
+	center: [],
+	small: [],
 };