diff --git a/autoware_launch/config/localization/ndt_scan_matcher.param.yaml b/autoware_launch/config/localization/ndt_scan_matcher.param.yaml
index 4a22059bda..decb56f1dc 100644
--- a/autoware_launch/config/localization/ndt_scan_matcher.param.yaml
+++ b/autoware_launch/config/localization/ndt_scan_matcher.param.yaml
@@ -40,6 +40,11 @@
     # The number of particles to estimate initial pose
     initial_estimate_particles_num: 100
 
+    # The number of initial random trials in the TPE (Tree-Structured Parzen Estimator).
+    # This value should be equal to or less than 'initial_estimate_particles_num' and more than 0.
+    # If it is equal to 'initial_estimate_particles_num', the search will be the same as a full random search.
+    n_startup_trials: 30
+
     # Tolerance of timestamp difference between current time and sensor pointcloud. [sec]
     lidar_topic_timeout_sec: 1.0