A registration unit associates identification information of a portable terminal device with identification information of a vehicle, which is to be registered and equipped with a communication device. The registration unit registers the identification information. A grant unit grants an authentication key to the portable terminal device having the registered identification information. A permission unit permits the portable terminal device with the authentication key to operate in cooperation with the communication device, which is equipped to a vehicle to be registered, and the communication device equipped to a vehicle other than the vehicle to be registered. The permission unit does not to permit the portable terminal device without the authentication key to operate in cooperation with the communication device equipped to any vehicle.