diff --git a/adf_core_python/core/agent/agent.py b/adf_core_python/core/agent/agent.py
index 6c8275b..b18fb67 100644
--- a/adf_core_python/core/agent/agent.py
+++ b/adf_core_python/core/agent/agent.py
@@ -24,10 +24,10 @@
 from rcrs_core.connection.URN import Entity as EntityURN
 from rcrs_core.messages.AKAcknowledge import AKAcknowledge
 from rcrs_core.messages.AKConnect import AKConnect
+from rcrs_core.messages.controlMessageFactory import ControlMessageFactory
 from rcrs_core.messages.KAConnectError import KAConnectError
 from rcrs_core.messages.KAConnectOK import KAConnectOK
 from rcrs_core.messages.KASense import KASense
-from rcrs_core.messages.controlMessageFactory import ControlMessageFactory
 from rcrs_core.worldmodel.changeSet import ChangeSet
 from rcrs_core.worldmodel.entityID import EntityID
 from rcrs_core.worldmodel.worldmodel import WorldModel
@@ -214,11 +214,6 @@ def update_step_info(
 
         self.think()
 
-        self.logger.debug(
-            f"send messages: {self._message_manager.get_send_message_list()}",
-            message_manager=self._message_manager,
-        )
-
         self._message_manager.coordinate_message(
             self._agent_info, self._world_info, self._scenario_info
         )
diff --git a/adf_core_python/core/logger/logger.py b/adf_core_python/core/logger/logger.py
index 766e283..16797e8 100644
--- a/adf_core_python/core/logger/logger.py
+++ b/adf_core_python/core/logger/logger.py
@@ -1,6 +1,7 @@
 import logging
+import os
 import sys
-from logging.handlers import RotatingFileHandler
+from datetime import datetime
 
 import structlog
 from structlog.dev import ConsoleRenderer
@@ -51,6 +52,13 @@ def get_agent_logger(name: str, agent_info: AgentInfo) -> structlog.BoundLogger:
 
 
 def configure_logger() -> None:
+    # 既存のログファイルが存在する場合、日付付きでバックアップする
+    log_file = "agent.log"
+    if os.path.exists(log_file):
+        timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
+        backup_file = f"agent_{timestamp}.log"
+        os.rename(log_file, backup_file)
+
     structlog.configure(
         processors=[
             structlog.stdlib.add_log_level,
@@ -65,16 +73,14 @@ def configure_logger() -> None:
         wrapper_class=structlog.stdlib.BoundLogger,
         cache_logger_on_first_use=True,
     )
+
     handler_stdout = logging.StreamHandler(sys.stdout)
     handler_stdout.setFormatter(
         structlog.stdlib.ProcessorFormatter(processor=ConsoleRenderer())
     )
     handler_stdout.setLevel(logging.INFO)
 
-    handler_file = RotatingFileHandler(
-        "agent.log", maxBytes=1024 * 1024 * 1024, backupCount=5
-    )
-    handler_file.doRollover()
+    handler_file = logging.FileHandler(log_file)
     handler_file.setFormatter(
         structlog.stdlib.ProcessorFormatter(processor=JSONRenderer())
     )