An object of the present invention is to provide flexibility in modifying or updating a communication system and the like of a vehicle-mounted network, thus reducing processing loads on electrical components modules and the like. In the present invention, a connector device with communication-controlling capability takes charge of controlling a communication system of a vehicle-mounted network, so that an electrical components module is specialized for its inherent processing other than the communication system. A control program about the communication system is rewritably stored in a rewritable non-volatile storage device in the connector device with communication-controlling capability, and the communication system is modified or updated only by renewing the control program stored in the non-volatile storage device in the connector device with communication-controlling capability.