diff --git a/dpgen/dispatcher/SSHContext.py b/dpgen/dispatcher/SSHContext.py
index 9e355b5ed..35a7e5997 100644
--- a/dpgen/dispatcher/SSHContext.py
+++ b/dpgen/dispatcher/SSHContext.py
@@ -280,7 +280,7 @@ def _put_files(self,
         os.chdir(self.local_root)
         if os.path.isfile(of) :
             os.remove(of)
-        with tarfile.open(of, "w:gz", dereference = dereference) as tar:
+        with tarfile.open(of, "w:gz", dereference = dereference, compresslevel=6) as tar:
             for ii in files :
                 tar.add(ii)
         os.chdir(cwd)