A piece of anomaly detection data that is the subject of determination is referred to as target data. The position of a vehicle when an anomaly occurred is grasped based on the target data. The number of pieces of the anomaly detection data is defined as the number of pieces of the anomaly detection data output within a predetermined area from the position of the vehicle when the anomaly occurred that is grasped based on the target data among the anomaly detection data stored in the memory. It is determined that the possibility that the target data is generated due to repair of the vehicle is higher when the number of pieces of the anomaly detection data is greater than or equal to a predetermined number than when the number of pieces of the anomaly detection data is less than the predetermined number.