diff --git a/.gitignore b/.gitignore
index 7ee1f598..e82650a2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,8 +10,10 @@
 *.log
 
 logs/*.txt
+api_log.db
 d_log/*.txt
 d_log/*.zip
+d_log/*.db
 sess_*
 */logs/*.txt
 */logs/*/*.txt
diff --git a/f_install/sql/api_log.sql b/f_install/sql/api_log.sql
new file mode 100644
index 00000000..4cc67f63
--- /dev/null
+++ b/f_install/sql/api_log.sql
@@ -0,0 +1,17 @@
+CREATE TABLE IF NOT EXISTS "api_log" (
+	"id"	INTEGER NOT NULL,
+	"user_id"	INTEGER NOT NULL,
+	"ip"	TEXT NOT NULL,
+	"date"	TEXT NOT NULL,
+	"path"	TEXT NOT NULL,
+	"arg"	TEXT,
+	"aux"	TEXT,
+	PRIMARY KEY("id" AUTOINCREMENT)
+);
+CREATE INDEX IF NOT EXISTS "by_date" ON "api_log" (
+	"date"	DESC
+);
+CREATE INDEX IF NOT EXISTS "by_user" ON "api_log" (
+	"user_id"	ASC,
+	"date"	DESC
+);
diff --git a/src/sammo/APIHelper.php b/src/sammo/APIHelper.php
index 3eaf3817..a4cf7a25 100644
--- a/src/sammo/APIHelper.php
+++ b/src/sammo/APIHelper.php
@@ -34,15 +34,42 @@ class APIHelper
             $input = [];
         }
 
+        if(class_exists('\\sammo\\UniqueConst')){
+            $serverID = UniqueConst::$serverID;
+            $logPath = "{$rootPath}/logs/{$serverID}/api_log.db";
+        }
+        else{
+            $realYearMonth = date('Y_m');
+            $logPath = "{$rootPath}/d_log/{$realYearMonth}_api_log.db";
+        }
+        $logDB = FileDB::db($logPath, __DIR__.'/../../f_install/sql/api_log.sql');
+        $ip = $_SERVER['REMOTE_ADDR'] ?? 'local';
+        $date = date('Y-m-d H:i:s');
+
         //NOTE: array_merge([], {})의 상황이 가능함.
         $actionArgs = array_merge($input, $eParams);
 
+        $filteredArgs = $actionArgs;
+
         try {
             $obj = buildAPIExecutorClass($actionPath, $rootPath, $actionArgs);
             $validateResult = $obj->validateArgs();
             if ($validateResult !== null) {
+                $logDB->insert('api_log', [
+                    'user_id' => 0,
+                    'ip' => $ip,
+                    'date' => $date,
+                    'path' => $actionPath,
+                    'arg' => JSON::encode($filteredArgs),
+                    'aux' => JSON::encode([
+                        'result'=>false,
+                        'state'=>'validate',
+                        'reason'=>$validateResult
+                    ]),
+                ]);
                 Json::dieWithReason($validateResult);
             }
+            $filteredArgs = $obj->getFilteredArgs();
 
             $sessionMode = $obj->getRequiredSessionMode();
             if ($sessionMode === BaseAPI::NO_SESSION) {
@@ -66,6 +93,18 @@ class APIHelper
 
             $result = $obj->launch($session, $modifiedSince, $reqEtags);
             if (is_string($result)) {
+                $logDB->insert('api_log', [
+                    'user_id' => $session->userID,
+                    'ip' => $ip,
+                    'date' => $date,
+                    'path' => $actionPath,
+                    'arg' => JSON::encode($filteredArgs),
+                    'aux' => JSON::encode([
+                        'result'=>false,
+                        'state'=>'launch',
+                        'reason'=>$validateResult
+                    ]),
+                ]);
                 Json::dieWithReason($result);
             }
 
@@ -82,28 +121,117 @@ class APIHelper
                     $lastModifiedUnixTime = Util::toInt(TimeUtil::DateTimeToSeconds($cache->lastModified, true));
                     $modifiedSinceUnixTime = Util::toInt(TimeUtil::DateTimeToSeconds($modifiedSince));
                     if($lastModifiedUnixTime === $modifiedSinceUnixTime){
+                        $logDB->insert('api_log', [
+                            'user_id' => $session->userID,
+                            'ip' => $ip,
+                            'date' => $date,
+                            'path' => $actionPath,
+                            'arg' => JSON::encode($filteredArgs),
+                            'aux' => JSON::encode([
+                                'result'=>true,
+                                'state'=>'cache_not_modified',
+                            ]),
+                        ]);
                         WebUtil::dieWithNotModified();
                     }
                 }
                 if ($reqEtags !== null && $reqEtags === $cache->etag) {
+                    $logDB->insert('api_log', [
+                        'user_id' => $session->userID,
+                        'ip' => $ip,
+                        'date' => $date,
+                        'path' => $actionPath,
+                        'arg' => JSON::encode($filteredArgs),
+                        'aux' => JSON::encode([
+                            'result'=>true,
+                            'state'=>'cache_not_modified',
+                        ]),
+                    ]);
                     WebUtil::dieWithNotModified();
                 }
             }
 
             if ($result === null) {
+                $logDB->insert('api_log', [
+                    'user_id' => $session->userID,
+                    'ip' => $ip,
+                    'date' => $date,
+                    'path' => $actionPath,
+                    'arg' => JSON::encode($filteredArgs),
+                    'aux' => JSON::encode([
+                        'result'=>true,
+                        'state'=>'success_simple',
+                        'set_cache'=>$setCache,
+                    ]),
+                ]);
                 Json::die([
                     'result' => true,
                     'reason' => 'success'
                 ], $setCache ? 0 : Json::NO_CACHE);
             }
+            $logDB->insert('api_log', [
+                'user_id' => $session->userID,
+                'ip' => $ip,
+                'date' => $date,
+                'path' => $actionPath,
+                'arg' => JSON::encode($filteredArgs),
+                'aux' => JSON::encode([
+                    'result'=>true,
+                    'state'=>'success_complex',
+                    'set_cache'=>$setCache,
+                ]),
+            ]);
             Json::die($result, $setCache ? 0 : Json::NO_CACHE);
         } catch (\Exception $e) {
-            Json::dieWithReason($e->getMessage()."\n".$e->getTraceAsString());
+            $errMsg = $e->getMessage();
+            $errTrace = $e->getTraceAsString();
+            $logDB->insert('api_log', [
+                'user_id' => $session->userID,
+                'ip' => $ip,
+                'date' => $date,
+                'path' => $actionPath,
+                'arg' => JSON::encode($filteredArgs),
+                'aux' => JSON::encode([
+                    'result'=>false,
+                    'state'=>'error_exception',
+                    'errMsg'=>$errMsg,
+                    'errTrace'=>$errTrace,
+                ]),
+            ]);
+            Json::dieWithReason("{$errMsg}\n{$errTrace}");
         } catch (\Throwable $e) {
             logExceptionByCustomHandler($e, false);
-            Json::dieWithReason($e->getMessage()."\n".$e->getTraceAsString());
+            $errMsg = $e->getMessage();
+            $errTrace = $e->getTraceAsString();
+            $logDB->insert('api_log', [
+                'user_id' => $session->userID,
+                'ip' => $ip,
+                'date' => $date,
+                'path' => $actionPath,
+                'arg' => JSON::encode($filteredArgs),
+                'aux' => JSON::encode([
+                    'result'=>false,
+                    'state'=>'error_throwable',
+                    'errMsg'=>$errMsg,
+                    'errTrace'=>$errTrace,
+                ]),
+            ]);
+            Json::dieWithReason("{$errMsg}\n{$errTrace}");
         } catch (mixed $e) {
-            Json::dieWithReason(strval($e));
+            $errStr = strval($e);
+            $logDB->insert('api_log', [
+                'user_id' => $session->userID,
+                'ip' => $ip,
+                'date' => $date,
+                'path' => $actionPath,
+                'arg' => JSON::encode($filteredArgs),
+                'aux' => JSON::encode([
+                    'result'=>false,
+                    'state'=>'error_mixed',
+                    'errMsg'=>$errStr,
+                ]),
+            ]);
+            Json::dieWithReason($errStr);
         }
     }
 }