VEHICLE-MOUNTED RELAY DEVICE, RELAY METHOD AND PROGRAM

An in-vehicle relay device that is installed in a vehicle and relays transmission and reception of data among in-vehicle equipment, includes a first communication unit that transmits and receives data to and from a first in-vehicle equipment, a second communication unit that transmits and receives data to and from a second in-vehicle equipment, and a control unit that controls relay of data among the first communication unit and the second communication unit. In a case where reception data received from the first communication unit or the second communication unit is unauthorized, the control unit stops the relaying in accordance with a traveling state of the vehicle.