diff --git a/config.php b/config.php
index d4ad12e70..27820488d 100644
--- a/config.php
+++ b/config.php
@@ -156,4 +156,7 @@ define('G5_SMTP', '127.0.0.1');
 // 게시판에서 링크의 기본개수를 말합니다.
 // 필드를 추가하면 이 숫자를 필드수에 맞게 늘려주십시오.
 define('G5_LINK_COUNT', 2);
+
+// 썸네일 jpg Quality 설정
+define('G5_THUMB_JPG_QUALITY', 90);
 ?>
\ No newline at end of file
diff --git a/lib/thumbnail.lib.php b/lib/thumbnail.lib.php
index caf04acc1..3f71de35a 100644
--- a/lib/thumbnail.lib.php
+++ b/lib/thumbnail.lib.php
@@ -356,7 +356,12 @@ function thumbnail($filename, $source_path, $target_path, $thumb_width, $thumb_h
         UnsharpMask($dst, $val[0], $val[1], $val[2]);
     }
 
-    imagejpeg($dst, $thumb_file, 90);
+    if(!defined('G5_THUMB_JPG_QUALITY'))
+        $jpg_quality = 90;
+    else
+        $jpg_quality = G5_THUMB_JPG_QUALITY;
+
+    imagejpeg($dst, $thumb_file, $jpg_quality);
     chmod($thumb_file, G5_FILE_PERMISSION); // 추후 삭제를 위하여 파일모드 변경
 
     imagedestroy($src);