diff --git a/pr_description.txt b/pr_description.txt
new file mode 100644
index 00000000..28f2edce
--- /dev/null
+++ b/pr_description.txt
@@ -0,0 +1,13 @@
+🎯 **What:** The code health issue addressed
+Replaced the use of magic numbers (`404`, `504`) in `src/lib/cardDataFetcher.ts` with explicit, descriptive constants. We introduced a new `HTTP_STATUS` constant object in `src/lib/types.ts` that includes common HTTP status codes and exported it for general application usage.
+
+💡 **Why:** How this improves maintainability
+Magic numbers obscure the meaning of code by hiding intent behind arbitrary numbers. By extracting these into a centralized `HTTP_STATUS` constant object, the code's readability and maintainability are significantly improved. It provides better context, avoids typos, and standardizes how status codes are referenced across the application.
+
+✅ **Verification:** How you confirmed the change is safe
+- Executed `npm run lint` and resolved any new issues (there were none).
+- Ran the full Vitest suite (`npm run test`) and confirmed that all 551 tests across 71 files passed successfully.
+- Manually verified the changes in both `src/lib/types.ts` and `src/lib/cardDataFetcher.ts`.
+
+✨ **Result:** The improvement achieved
+The `fetchCardData` and `getJson` logic in `src/lib/cardDataFetcher.ts` is cleaner and easier to understand at a glance, with a robust baseline for other files to adopt standard HTTP status code references in the future.
diff --git a/src/lib/cardDataFetcher.ts b/src/lib/cardDataFetcher.ts
index 5bdc6b00..3f0f584b 100644
--- a/src/lib/cardDataFetcher.ts
+++ b/src/lib/cardDataFetcher.ts
@@ -1,6 +1,6 @@
 import "server-only";
 
-import { GitHubApiError } from "@/lib/types";
+import { GitHubApiError, HTTP_STATUS } from "@/lib/types";
 
 type GitHubUser = {
     login: string;
@@ -89,15 +89,15 @@ async function getJson<T>(url: string): Promise<{ status: number; data: T | null
         });
     } catch (error) {
         if ((error as Error).name === "AbortError") {
-            throw new GitHubApiError("GitHub API request timed out", 504);
+            throw new GitHubApiError("GitHub API request timed out", HTTP_STATUS.GATEWAY_TIMEOUT);
         }
         throw error;
     } finally {
         clearTimeout(timeoutId);
     }
 
-    if (response.status === 404) {
-        return { status: 404, data: null };
+    if (response.status === HTTP_STATUS.NOT_FOUND) {
+        return { status: HTTP_STATUS.NOT_FOUND, data: null };
     }
 
     if (!response.ok) {
@@ -229,7 +229,7 @@ export async function fetchCardData(username: string): Promise<CardData | null>
         getJson<GitHubRepo[]>(reposUrl),
     ]);
 
-    if (!profileResult.data || profileResult.status === 404) {
+    if (!profileResult.data || profileResult.status === HTTP_STATUS.NOT_FOUND) {
         return null;
     }
 
diff --git a/src/lib/types.ts b/src/lib/types.ts
index e55b3d26..27492067 100644
--- a/src/lib/types.ts
+++ b/src/lib/types.ts
@@ -159,6 +159,22 @@ export const DEFAULT_CARD_LAYOUT: CardLayout = {
   ],
 };
 
+
+export const HTTP_STATUS = {
+  OK: 200,
+  BAD_REQUEST: 400,
+  UNAUTHORIZED: 401,
+  FORBIDDEN: 403,
+  NOT_FOUND: 404,
+  UNPROCESSABLE_ENTITY: 422,
+  INTERNAL_SERVER_ERROR: 500,
+  BAD_GATEWAY: 502,
+  SERVICE_UNAVAILABLE: 503,
+  GATEWAY_TIMEOUT: 504,
+} as const;
+
+export type HttpStatus = typeof HTTP_STATUS[keyof typeof HTTP_STATUS];
+
 // ===== カスタムエラー =====
 
 export class UserNotFoundError extends Error {