An automatic upgrading method in which, when software is downloaded and upgraded to change a specification of a software defined radio system on a vehicular system, convenience to a user who receives services using wireless communication is not reduced and error operations of the vehicular system is inhibited, is provided. A state in which a vehicle is not used is the most appropriate for the upgrade. It is determined whether a key is removed. When the key is removed, the download is executed using wireless communications. After that, a software defined radio system and a car navigation system are stopped. The upgrade and test operation are executed. When the test result is good, the software defined radio system and the car navigation system are restarted.