Inner vehicle communication system and gateway

An inner vehicle communication system and a gateway are provided to construct a CAN(Controller Area Network) communication system by using existing electrical components as they are, and to reduce weight of wires equipped inside a vehicle, thereby improving fuel efficiency of the vehicle. A CAN communication group(10) is composed of CAN buses(HS_CAN_HI,HS_CAN_LO,LS_AN_HI,LS_CAN_LO) and a lot of electrical components(11-16) connected to the CAN buses(HS_CAN_HI,HS_CAN_LO,LS_AN_HI,LS_CAN_LO). A general electric wire communication group(30) is composed of general electric wires and a lot of electrical components connected to the general electric wires. A gateway(50) is connected between the CAN communication group(10) and the general electric wire communication group(30), and carries out a protocol relay function.