diff --git a/worker/api_receiver.php b/worker/api_receiver.php
index 796c18f..fd3e649 100644
--- a/worker/api_receiver.php
+++ b/worker/api_receiver.php
@@ -115,9 +115,21 @@ function writeLog($message, $level = 'ERROR') {
 }
 
 // 도우미 함수 정의
+function safeJsonEncode($value, $flags = 0, $depth = 512) {
+    try {
+        return json_encode($value, $flags | JSON_THROW_ON_ERROR, $depth);
+    } catch (JsonException $e) {
+        return false;
+    }
+}
+
 function apiResponse($error = null) {
-    $base = $error;
-    return json_encode($base);
+    $encoded = safeJsonEncode($error, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+    if ($encoded === false) {
+        writeLog('JSON_ENCODE_FAIL | apiResponse encoding failed', 'ERROR');
+        return '{"code":"E999","message":"Internal server error"}';
+    }
+    return $encoded;
 }
 
 // 1. 응답 헤더 설정 (JSON)
@@ -128,7 +140,12 @@ $protocol = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "
 $fullUrl = $protocol . "://" . ($_SERVER['HTTP_HOST'] ?? 'localhost') . ($_SERVER['REQUEST_URI'] ?? '');
 $rawData = file_get_contents('php://input');
 
-writeLog("REQUEST_INFO | " . json_encode($rawData, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES), 'INFO');
+$rawDataLog = safeJsonEncode($rawData, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+if ($rawDataLog === false) {
+    writeLog('JSON_ENCODE_FAIL | failed to encode raw request data for logging', 'WARNING');
+    $rawDataLog = '"json_encode_failed"';
+}
+writeLog("REQUEST_INFO | " . $rawDataLog, 'INFO');
 
 $requestInfo = [
     'timestamp' => date('Y-m-d H:i:s'),
@@ -150,7 +167,12 @@ $requestInfo = [
     'server_protocol' => $_SERVER['SERVER_PROTOCOL'] ?? '',
 ];
 
-writeLog("REQUEST_INFO | " . json_encode($requestInfo, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES), 'INFO');
+$requestInfoLog = safeJsonEncode($requestInfo, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+if ($requestInfoLog === false) {
+    writeLog('JSON_ENCODE_FAIL | failed to encode request metadata for logging', 'WARNING');
+    $requestInfoLog = '"json_encode_failed"';
+}
+writeLog("REQUEST_INFO | " . $requestInfoLog, 'INFO');
 // ================================================================
 
 // 2. 보안 키 체크 (URL 파라미터 key=값)
@@ -231,7 +253,12 @@ try {
         $redis->select((int)$redisDatabase);
 
         // 'naver:raw_queue'라는 이름의 리스트에 저장
-        $pushResult = $redis->lPush('naver:raw_queue', json_encode($payload));
+        $encodedPayload = safeJsonEncode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+        if ($encodedPayload === false) {
+            throw new Exception('Failed to encode payload for Redis queue');
+        }
+
+        $pushResult = $redis->lPush('naver:raw_queue', $encodedPayload);
         
         if (!$pushResult) {
             throw new Exception("Failed to push data to Redis queue");
@@ -255,7 +282,12 @@ try {
 
         // 파일로 저장 (타임스탬프 + 유니크ID)
         $filename = $fallbackDir . '/' . date('YmdHis') . '_' . uniqid() . '.json';
-        $writeResult = file_put_contents($filename, json_encode($payload), LOCK_EX);
+        $encodedPayload = safeJsonEncode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+        if ($encodedPayload === false) {
+            throw new Exception('Failed to encode payload for fallback file');
+        }
+
+        $writeResult = file_put_contents($filename, $encodedPayload, LOCK_EX);
         
         if ($writeResult === false) {
             throw new Exception("Failed to write fallback file");