diff --git a/apps/sn/src/features/ctyFldngPrvtnBiz/ui/CtyFldngPrvtnBizFormPage.tsx b/apps/sn/src/features/ctyFldngPrvtnBiz/ui/CtyFldngPrvtnBizFormPage.tsx
index c49c8c673..f0507195b 100644
--- a/apps/sn/src/features/ctyFldngPrvtnBiz/ui/CtyFldngPrvtnBizFormPage.tsx
+++ b/apps/sn/src/features/ctyFldngPrvtnBiz/ui/CtyFldngPrvtnBizFormPage.tsx
@@ -393,6 +393,8 @@ export function CtyFldngPrvtnBizFormPage({ id }: { id?: string }) {
       suggestionOptions.length > 0 ? `${fieldId}-suggestions` : undefined;
     const span: 1 | 2 | 3 =
       key === "excptnMttrCn" ? 3 : key === "bizNm" || key === "pstn" ? 2 : 1;
+    // 수정 화면에서는 중복 판정 업무키인 사업순번과 단계를 변경할 수 없다.
+    const isBusinessKeyLocked = Boolean(id) && (key === "seqNo" || key === "stp");
     return (
       <StandardFormField
         key={key}
@@ -408,6 +410,7 @@ export function CtyFldngPrvtnBizFormPage({ id }: { id?: string }) {
             maxLength={standardMaxLengths[key]}
             type={type === "date" ? "date" : type}
             list={suggestionListId}
+            disabled={isBusinessKeyLocked}
             value={String(form[key] ?? "")}
             onChange={(event) =>
               setForm((current) => ({