diff --git a/bert_gen.py b/bert_gen.py
index 933fa21..1e4a92c 100644
--- a/bert_gen.py
+++ b/bert_gen.py
@@ -6,15 +6,19 @@ import torch.multiprocessing as mp
 from tqdm import tqdm
 
 from config import config
+from style_bert_vits2.constants import Languages
 from style_bert_vits2.logging import logger
 from style_bert_vits2.models import commons
 from style_bert_vits2.models.hyper_parameters import HyperParameters
-from style_bert_vits2.nlp import cleaned_text_to_sequence, extract_bert_feature
+from style_bert_vits2.nlp import (
+    bert_models,
+    cleaned_text_to_sequence,
+    extract_bert_feature,
+)
 from style_bert_vits2.nlp.japanese import pyopenjtalk_worker
 from style_bert_vits2.nlp.japanese.user_dict import update_dict
 from style_bert_vits2.utils.stdout_wrapper import SAFE_STDOUT
-from style_bert_vits2.nlp import bert_models
-from style_bert_vits2.constants import Languages
+
 
 bert_models.load_model(Languages.JP)
 bert_models.load_tokenizer(Languages.JP)
@@ -74,9 +78,6 @@ if __name__ == "__main__":
     parser.add_argument(
         "-c", "--config", type=str, default=config.bert_gen_config.config_path
     )
-    parser.add_argument(
-        "--num_processes", type=int, default=config.bert_gen_config.num_processes
-    )
     args, _ = parser.parse_known_args()
     config_path = args.config
     hps = HyperParameters.load_from_json(config_path)
@@ -89,7 +90,8 @@ if __name__ == "__main__":
     add_blank = [hps.data.add_blank] * len(lines)
 
     if len(lines) != 0:
-        num_processes = args.num_processes
+        # pyopenjtalkの別ワーカー化により、並列処理でエラーがでる模様なので、一旦シングルスレッド強制にする
+        num_processes = 1
         with ThreadPoolExecutor(max_workers=num_processes) as executor:
             _ = list(
                 tqdm(
diff --git a/config.py b/config.py
index 40f3f53..2229e61 100644
--- a/config.py
+++ b/config.py
@@ -92,7 +92,7 @@ class Bert_gen_config:
     def __init__(
         self,
         config_path: str,
-        num_processes: int = 2,
+        num_processes: int = 1,
         device: str = "cuda",
         use_multi_device: bool = False,
     ):
diff --git a/default_config.yml b/default_config.yml
index ca51e7f..8060cfb 100644
--- a/default_config.yml
+++ b/default_config.yml
@@ -22,7 +22,7 @@ preprocess_text:
 
 bert_gen:
   config_path: "config.json"
-  num_processes: 2
+  num_processes: 1
   device: "cuda"
   use_multi_device: false