diff --git a/backend-spring/src/main/java/com/erp/service/BatchManagementService.java b/backend-spring/src/main/java/com/erp/service/BatchManagementService.java
index fbb88f0e..2ee2786c 100644
--- a/backend-spring/src/main/java/com/erp/service/BatchManagementService.java
+++ b/backend-spring/src/main/java/com/erp/service/BatchManagementService.java
@@ -200,9 +200,18 @@ public class BatchManagementService extends BaseService {
     // ── REST API Preview / Save ───────────────────────────────────────────────
 
     public Map<String, Object> previewRestApiData(Map<String, Object> body) {
-        // 프론트는 camelCase 로 보내고 백엔드는 snake_case 로 읽음 — 변환 필요
-        // (updateBatchConfig / executeBatchConfig 와 동일 패턴. 누락되어 있던 것을 보강)
-        convertCamelToSnake(body);
+        // 프론트(batchManagement.ts)는 camelCase 로 키를 보내고 백엔드는 snake_case 로 읽음.
+        // 기존 convertCamelToSnake() 는 batch_configs 전용 remap 이라 여기엔 효과 없음.
+        // → previewRestApiData 전용으로 사용하는 키만 직접 remap.
+        remap(body, "apiUrl",          "api_url");
+        remap(body, "apiKey",          "api_key");
+        remap(body, "requestBody",     "request_body");
+        remap(body, "dataArrayPath",   "data_array_path");
+        remap(body, "paramType",       "param_type");
+        remap(body, "paramName",       "param_name");
+        remap(body, "paramValue",      "param_value");
+        remap(body, "paramSource",     "param_source");
+        remap(body, "authServiceName", "auth_service_name");
 
         String apiUrl     = str(body.get("api_url"));
         String endpoint   = str(body.get("endpoint"));
diff --git a/frontend/app/(main)/admin/batch-management-new/page.tsx b/frontend/app/(main)/admin/batch-management-new/page.tsx
index 156d083c..7e5ded4b 100644
--- a/frontend/app/(main)/admin/batch-management-new/page.tsx
+++ b/frontend/app/(main)/admin/batch-management-new/page.tsx
@@ -721,7 +721,7 @@ export default function BatchManagementNewPage() {
   const goBack = () => openTab({ type: "admin", title: "배치 관리", admin_url: "/admin/automaticMng/batchmngList" });
 
   return (
-    <div className="w-full space-y-6 p-4 sm:p-6">
+    <div className="h-full w-full space-y-6 overflow-y-auto p-4 sm:p-6">
       {/* 헤더 */}
       <div className="flex items-center justify-between">
         <div className="flex items-center gap-3">
@@ -1630,30 +1630,30 @@ const RestApiToDbMappingCard = memo(function RestApiToDbMappingCard({
 
   return (
     <Card>
-      <CardHeader>
-        <CardTitle>컬럼 매핑 설정</CardTitle>
-        <CardDescription>DB 컬럼에 API 필드 또는 고정값을 매핑합니다.</CardDescription>
+      <CardHeader className="px-4 pb-2 pt-3">
+        <CardTitle className="text-sm">컬럼 매핑 설정</CardTitle>
+        <CardDescription className="text-[11px]">DB 컬럼에 API 필드 또는 고정값을 매핑합니다.</CardDescription>
       </CardHeader>
-      <CardContent>
-        <div className="grid grid-cols-1 gap-6 lg:grid-cols-2">
+      <CardContent className="px-4 pb-3 pt-0">
+        <div className="grid grid-cols-1 gap-3 lg:grid-cols-2">
           {/* 왼쪽: 샘플 데이터 */}
           <div className="flex flex-col">
-            <div className="mb-3 flex h-8 items-center">
-              <h4 className="text-sm font-semibold">샘플 데이터 (최대 3개)</h4>
+            <div className="mb-2 flex h-7 items-center">
+              <h4 className="text-xs font-semibold">샘플 데이터 (최대 3개)</h4>
             </div>
             {sampleJsonList.length > 0 ? (
-              <div className="bg-muted/30 h-[360px] overflow-y-auto rounded-lg border p-3">
-                <div className="space-y-2">
+              <div className="bg-muted/30 h-[300px] overflow-y-auto rounded-lg border p-2">
+                <div className="space-y-1.5">
                   {sampleJsonList.map((json, index) => (
-                    <div key={index} className="bg-background rounded border p-2">
-                      <pre className="font-mono text-xs whitespace-pre-wrap">{json}</pre>
+                    <div key={index} className="bg-background rounded border p-1.5">
+                      <pre className="font-mono text-[11px] whitespace-pre-wrap">{json}</pre>
                     </div>
                   ))}
                 </div>
               </div>
             ) : (
-              <div className="flex h-[360px] items-center justify-center rounded-lg border border-dashed">
-                <p className="text-muted-foreground text-sm">
+              <div className="flex h-[300px] items-center justify-center rounded-lg border border-dashed">
+                <p className="text-muted-foreground text-xs">
                   API 데이터 미리보기를 실행하면 샘플 데이터가 표시됩니다.
                 </p>
               </div>
@@ -1662,39 +1662,39 @@ const RestApiToDbMappingCard = memo(function RestApiToDbMappingCard({
 
           {/* 오른쪽: 매핑 영역 (스크롤) */}
           <div className="flex flex-col">
-            <div className="mb-3 flex h-8 items-center justify-between">
-              <h4 className="text-sm font-semibold">매핑 설정</h4>
-              <Button variant="outline" size="sm" onClick={addMapping} className="h-8 gap-1">
-                <Plus className="h-4 w-4" />
+            <div className="mb-2 flex h-7 items-center justify-between">
+              <h4 className="text-xs font-semibold">매핑 설정</h4>
+              <Button variant="outline" size="sm" onClick={addMapping} className="h-7 gap-1 px-2 text-[11px]">
+                <Plus className="h-3 w-3" />
                 매핑 추가
               </Button>
             </div>
 
             {mappingList.length === 0 ? (
-              <div className="flex h-[360px] flex-col items-center justify-center rounded-lg border border-dashed text-center">
-                <p className="text-muted-foreground text-sm">매핑이 없습니다.</p>
-                <Button variant="link" onClick={addMapping} className="mt-2">
+              <div className="flex h-[300px] flex-col items-center justify-center rounded-lg border border-dashed text-center">
+                <p className="text-muted-foreground text-xs">매핑이 없습니다.</p>
+                <Button variant="link" size="sm" onClick={addMapping} className="mt-1 h-auto text-xs">
                   매핑 추가하기
                 </Button>
               </div>
             ) : (
-              <div className="bg-muted/30 h-[360px] space-y-3 overflow-y-auto rounded-lg border p-3">
+              <div className="bg-muted/30 h-[300px] space-y-2 overflow-y-auto rounded-lg border p-2">
                 {mappingList.map((mapping, index) => (
-                  <div key={mapping.id} className="bg-background flex items-center gap-2 rounded-lg border p-3">
+                  <div key={mapping.id} className="bg-background flex items-center gap-1.5 rounded-lg border p-2">
                     {/* 순서 표시 */}
-                    <div className="bg-primary/10 text-primary flex h-6 w-6 shrink-0 items-center justify-center rounded-full text-xs font-medium">
+                    <div className="bg-primary/10 text-primary flex h-5 w-5 shrink-0 items-center justify-center rounded-full text-[10px] font-medium">
                       {index + 1}
                     </div>
 
                     {/* DB 컬럼 선택 (좌측 - TO) */}
-                    <div className="w-36 shrink-0">
+                    <div className="w-32 shrink-0">
                       <Select
                         value={mapping.dbColumn || "none"}
                         onValueChange={(value) =>
                           updateMapping(mapping.id, { dbColumn: value === "none" ? "" : value })
                         }
                       >
-                        <SelectTrigger className="h-9">
+                        <SelectTrigger className="h-7 text-xs">
                           <SelectValue placeholder="DB 컬럼" />
                         </SelectTrigger>
                         <SelectContent>
@@ -1716,10 +1716,10 @@ const RestApiToDbMappingCard = memo(function RestApiToDbMappingCard({
                     </div>
 
                     {/* 화살표 */}
-                    <ArrowLeft className="text-muted-foreground h-4 w-4 shrink-0" />
+                    <ArrowLeft className="text-muted-foreground h-3.5 w-3.5 shrink-0" />
 
                     {/* 소스 타입 선택 */}
-                    <div className="w-28 shrink-0">
+                    <div className="w-24 shrink-0">
                       <Select
                         value={mapping.sourceType}
                         onValueChange={(value: "api" | "fixed" | "conditional") =>
@@ -1738,7 +1738,7 @@ const RestApiToDbMappingCard = memo(function RestApiToDbMappingCard({
                           })
                         }
                       >
-                        <SelectTrigger className="h-9">
+                        <SelectTrigger className="h-7 text-xs">
                           <SelectValue />
                         </SelectTrigger>
                         <SelectContent>
@@ -1758,7 +1758,7 @@ const RestApiToDbMappingCard = memo(function RestApiToDbMappingCard({
                             updateMapping(mapping.id, { apiField: value === "none" ? "" : value })
                           }
                         >
-                          <SelectTrigger className="h-9">
+                          <SelectTrigger className="h-7 text-xs">
                             <SelectValue placeholder="API 필드" />
                           </SelectTrigger>
                           <SelectContent>
@@ -1768,7 +1768,7 @@ const RestApiToDbMappingCard = memo(function RestApiToDbMappingCard({
                                 <div className="flex items-center gap-2">
                                   <span>{field}</span>
                                   {firstSample && firstSample[field] !== undefined && (
-                                    <span className="text-muted-foreground text-xs">
+                                    <span className="text-muted-foreground text-[10px]">
                                       (예: {String(firstSample[field]).substring(0, 15)}
                                       {String(firstSample[field]).length > 15 ? "..." : ""})
                                     </span>
@@ -1784,7 +1784,7 @@ const RestApiToDbMappingCard = memo(function RestApiToDbMappingCard({
                           value={mapping.fixedValue}
                           onChange={(e) => updateMapping(mapping.id, { fixedValue: e.target.value })}
                           placeholder="고정값 입력"
-                          className="h-9"
+                          className="h-7 text-xs"
                         />
                       )}
                       {mapping.sourceType === "conditional" && (
@@ -1807,9 +1807,9 @@ const RestApiToDbMappingCard = memo(function RestApiToDbMappingCard({
                       variant="ghost"
                       size="icon"
                       onClick={() => removeMapping(mapping.id)}
-                      className="text-muted-foreground hover:text-destructive h-8 w-8 shrink-0"
+                      className="text-muted-foreground hover:text-destructive h-6 w-6 shrink-0"
                     >
-                      <Trash2 className="h-4 w-4" />
+                      <Trash2 className="h-3.5 w-3.5" />
                     </Button>
                   </div>
                 ))}
diff --git a/frontend/lib/api/batchManagement.ts b/frontend/lib/api/batchManagement.ts
index ad880786..a0f666b0 100644
--- a/frontend/lib/api/batchManagement.ts
+++ b/frontend/lib/api/batchManagement.ts
@@ -164,7 +164,9 @@ class BatchManagementAPIClass {
         BatchApiResponse<{
           fields: string[];
           samples: any[];
-          totalCount: number;
+          // 백엔드는 snake_case (total_count) 로 응답하므로 두 키 모두 옵션으로 받음
+          total_count?: number;
+          totalCount?: number;
         }>
       >(`${this.BASE_PATH}/rest-api/preview`, requestData);
 
@@ -172,7 +174,13 @@ class BatchManagementAPIClass {
         throw new Error(response.data.message || "REST API 미리보기에 실패했습니다.");
       }
 
-      return response.data.data || { fields: [], samples: [], totalCount: 0 };
+      const raw = response.data.data;
+      return {
+        fields: raw?.fields ?? [],
+        samples: raw?.samples ?? [],
+        // 백엔드는 total_count 로 응답 → camelCase totalCount 로 normalize
+        totalCount: raw?.total_count ?? raw?.totalCount ?? 0,
+      };
     } catch (error) {
       console.error("REST API 미리보기 오류:", error);
       throw error;