diff --git a/netlify/edge-functions/bff-proxy.js b/netlify/edge-functions/bff-proxy.js
index e0f2acb..79629eb 100644
--- a/netlify/edge-functions/bff-proxy.js
+++ b/netlify/edge-functions/bff-proxy.js
@@ -154,7 +154,7 @@ export default async (request, context) => {
       qr.make();
       const moduleCount = qr.getModuleCount();
       const cellSize = Math.max(1, Math.floor(numSize / (moduleCount + QR_MARGIN_MODULES)));
-      const qrcode = qr.createDataURL(cellSize, cellSize * 2);
+      const qrcode = qr.createDataURL(cellSize, cellSize * 4);
 
       const duration = Date.now() - qrStartTime;
       console.log(`[edge:qrcode-generate] Success: size=${numSize}, modules=${moduleCount}, cellSize=${cellSize}, duration=${duration}ms, qrcodeLength=${qrcode.length}`);
diff --git a/src/js/modules/qrcode-generator.js b/src/js/modules/qrcode-generator.js
index 618d143..2ef6b72 100644
--- a/src/js/modules/qrcode-generator.js
+++ b/src/js/modules/qrcode-generator.js
@@ -213,8 +213,8 @@ export async function generateQRCodeLocal(data, size = DEFAULT_QR_SIZE, labels =
     const cellSize = Math.max(1, Math.floor(safeSize / (moduleCount + QR_MARGIN_MODULES)));
     const largeCellSize = Math.max(1, Math.floor(LARGE_PREVIEW_SIZE / (moduleCount + QR_MARGIN_MODULES)));
 
-    const imageUrl = qr.createDataURL(cellSize, 2);
-    const largeImageUrl = qr.createDataURL(largeCellSize, 2);
+    const imageUrl = qr.createDataURL(cellSize, cellSize * 4);
+    const largeImageUrl = qr.createDataURL(largeCellSize, largeCellSize * 4);
 
     console.log(`[QRCode] Local generation success: size=${safeSize}, modules=${moduleCount}, cellSize=${cellSize}`);