A CPU of a speech ECU acquires vehicle position information. If it is determined from the position information and map data stored in a memory that the vehicle has moved between areas where different languages are spoken as dialects or official languages, the CPU determines a language corresponding to the vehicle position information and transmits a request signal to a speech information center to transmit speech information in the language. By receiving the speech information from the speech information center, the CPU updates speech information pre-stored in the memory with the speech information transmitted from the speech information center.