diff --git a/B08_Quantity/B08_Quantity_UI_MaterialGrid.ts b/B08_Quantity/B08_Quantity_UI_MaterialGrid.ts
index 6c173438..e13fd55b 100644
--- a/B08_Quantity/B08_Quantity_UI_MaterialGrid.ts
+++ b/B08_Quantity/B08_Quantity_UI_MaterialGrid.ts
@@ -266,7 +266,9 @@ function surchargeCell(
   input.className = "b08-grid__select";
   input.style.width = "4.5em";
   const picked = picks[key];
-  input.value = String(picked ?? row.surcharge_pct ?? cap);
+  // 안 고른 칸은 **비워 두고 회색 제안값**(지금 붙는 표값)만 — 기본값을 값처럼 채우지 않음(폼 ② 규칙).
+  input.value = picked === null || picked === undefined ? "" : String(picked);
+  input.placeholder = String(row.surcharge_pct ?? cap);
   input.title = `표값 ${cap}% 이내(품셈 1-3-1) · 비우면 표값`;
   input.addEventListener("change", () => {
     const text = input.value.trim();
@@ -278,7 +280,6 @@ function surchargeCell(
     }
     input.setCustomValidity("");
     picks[key] = text === "" ? null : value;
-    if (text === "") input.value = String(cap);
     td.classList.add("is-changed");
     onChange();
   });