diff --git a/perception/tracking_object_merger/src/utils/utils.cpp b/perception/tracking_object_merger/src/utils/utils.cpp
index 90de9b6a41cbd..08680380f253c 100644
--- a/perception/tracking_object_merger/src/utils/utils.cpp
+++ b/perception/tracking_object_merger/src/utils/utils.cpp
@@ -323,6 +323,26 @@ autoware_auto_perception_msgs::msg::TrackedObjectKinematics objectKinematicsVXMe
   autoware_auto_perception_msgs::msg::TrackedObjectKinematics output_kinematics;
   // copy main object at first
   output_kinematics = main_obj.kinematics;
+
+    // if the main object is run opposite direction, flip the main object
+  if (output_kinematics.twist_with_covariance.twist.linear.x < 0.0) {
+    // flip velocity
+    output_kinematics.twist_with_covariance.twist.linear.x *= -1.0;
+    output_kinematics.twist_with_covariance.twist.linear.y *= -1.0;
+    // flip orientation, rotate 180 deg
+    const auto q = tf2::Quaternion(
+      output_kinematics.pose_with_covariance.pose.orientation.x,
+      output_kinematics.pose_with_covariance.pose.orientation.y,
+      output_kinematics.pose_with_covariance.pose.orientation.z,
+      output_kinematics.pose_with_covariance.pose.orientation.w);
+    const auto q_rot = tf2::Quaternion(tf2::Vector3(0, 0, 1), M_PI);
+    const auto q_rotated = q * q_rot;
+    output_kinematics.pose_with_covariance.pose.orientation.x = q_rotated.x();
+    output_kinematics.pose_with_covariance.pose.orientation.y = q_rotated.y();
+    output_kinematics.pose_with_covariance.pose.orientation.z = q_rotated.z();
+    output_kinematics.pose_with_covariance.pose.orientation.w = q_rotated.w();
+  }
+
   auto sub_obj_ = sub_obj;
   // do not merge reverse direction objects
   if (!objectsHaveSameMotionDirections(main_obj, sub_obj)) {