diff --git a/finetune/merge_dd_tags_to_metadata.py b/finetune/merge_dd_tags_to_metadata.py
index 8101ecd3..913fa90a 100644
--- a/finetune/merge_dd_tags_to_metadata.py
+++ b/finetune/merge_dd_tags_to_metadata.py
@@ -2,25 +2,33 @@
 # (c) 2022 Kohya S. @kohya_ss
 
 import argparse
-import glob
-import os
 import json
+from pathlib import Path
 
 from tqdm import tqdm
 
 
 def main(args):
-  image_paths = glob.glob(os.path.join(args.train_data_dir, "*.jpg")) + \
-      glob.glob(os.path.join(args.train_data_dir, "*.png")) + glob.glob(os.path.join(args.train_data_dir, "*.webp"))
+  
+  image_paths = None
+  train_data_dir_path = Path(args.train_data_dir)
+  if args.recursive_data_dir:
+    image_paths = list(train_data_dir_path.rglob('*.jpg')) + \
+                  list(train_data_dir_path.rglob('*.png')) + \
+                  list(train_data_dir_path.rglob('*.webp')) 
+  else:
+    image_paths = list(train_data_dir_path.glob('*.jpg')) + \
+                  list(train_data_dir_path.glob('*.png')) + \
+                  list(train_data_dir_path.glob('*.webp')) 
+
   print(f"found {len(image_paths)} images.")
 
-  if args.in_json is None and os.path.isfile(args.out_json):
+  if args.in_json is None and Path(args.out_json).is_file():
     args.in_json = args.out_json
 
   if args.in_json is not None:
     print(f"loading existing metadata: {args.in_json}")
-    with open(args.in_json, "rt", encoding='utf-8') as f:
-      metadata = json.load(f)
+    metadata = json.loads(Path(args.in_json).read_text(encoding='utf-8'))
     print("tags data for existing images will be overwritten / 既存の画像のタグは上書きされます")
   else:
     print("new metadata will be created / 新しいメタデータファイルが作成されます")
@@ -28,22 +36,21 @@ def main(args):
 
   print("merge tags to metadata json.")
   for image_path in tqdm(image_paths):
-    tags_path = os.path.splitext(image_path)[0] + '.txt'
-    with open(tags_path, "rt", encoding='utf-8') as f:
-      tags = f.readlines()[0].strip()
+    tags_path = image_path.with_suffix('.txt')
+    tags = tags_path.read_text(encoding='utf-8').strip()
 
-    image_key = image_path if args.full_path else os.path.splitext(os.path.basename(image_path))[0]
-    if image_key not in metadata:
-      metadata[image_key] = {}
+    image_key = image_path if args.full_path else image_path.stem
+    if str(image_key) not in metadata:
+      metadata[str(image_key)] = {}
 
-    metadata[image_key]['tags'] = tags
+    metadata[str(image_key)]['tags'] = tags
     if args.debug:
       print(image_key, tags)
 
   # metadataを書き出して終わり
   print(f"writing metadata: {args.out_json}")
-  with open(args.out_json, "wt", encoding='utf-8') as f:
-    json.dump(metadata, f, indent=2)
+  Path(args.out_json).write_text(json.dumps(metadata, indent=2), encoding='utf-8')
+    
   print("done!")
 
 
@@ -54,6 +61,7 @@ if __name__ == '__main__':
   parser.add_argument("--in_json", type=str, help="metadata file to input (if omitted and out_json exists, existing out_json is read) / 読み込むメタデータファイル（省略時、out_jsonが存在すればそれを読み込む）")
   parser.add_argument("--full_path", action="store_true",
                       help="use full path as image-key in metadata (supports multiple directories) / メタデータで画像キーをフルパスにする（複数の学習画像ディレクトリに対応）")
+  parser.add_argument("--recursive_data_dir", action="store_true", help="recursively look for training tags in all child folders of train_data_dir / train_data_dirのすべての子フォルダにある学習タグを再帰的に探す")
   parser.add_argument("--debug", action="store_true", help="debug mode, print tags")
 
   args = parser.parse_args()