A gateway that is mounted on a vehicle, includes: a communication unit that can communicate with an external device through other gateway capable of communicating with the external device outside the vehicle, wherein said other gateway includes a switch unit that executes relay processing of relaying communication data and a processing unit that controls the relay processing of the switch unit, wherein said communication unit can relay communication data received from said switch unit to a device inside said vehicle, said gateway further including: a control unit that determines abnormality in said other gateway and if it is determined that said abnormality occurs, controls relay processing of said other gateway.