A cellular phone unit (1) is provided with ID information input means for accepting an input of user ID information, ID judging means for judging whether or not the inputted user ID information is identical to pre-registered ID information, authentication information transmission permitting means for deciding whether or not to permit transmission of sender authentication information in accordance with the judgment result, and authentication information transmitting means for sending the sender authentication information in accordance with the decision. A vehicle-mounted control device (2) is provided with an antenna (5) and a transmission and reception section (6) for receiving the sender authentication information, and a control section (4) and an interface (7) for judging whether or not the sender authentication information received from the cellular phone unit (1) is identical to pre-registered authentication information and for controlling vehicle-mounted devices (3a) through (3c) in accordance with the judgment result.