The present disclosure provides a driving assistance system and a vehicle-mounted device. Each vehicle-mounted device broadcasts own vehicle information, and transmits wide area vehicle information to a center. The wide area vehicle information includes the vehicle information and VIN of the own vehicle. The center receives the wide area vehicle information, and stores the vehicle information and the VIN in a correlated manner in a center end database. The vehicle-mounted device transmits an appearance information request signal to the center. The appearance information request signal includes generation time and location information of a different vehicle. The center specifies, based on the generation time and the location information included in the appearance information request signal, the VIN of the vehicle requested by the vehicle-mounted device, and acquires the appearance information related to the specified VIN by searching the appearance information database, and then transmits the appearance information to the vehicle-mounted device.