An information processing device includes: a first communication unit which transmits and receives communication data through a network connected to a first GW, a second GW, and at least one electronic control unit; a monitoring unit which determines whether the communication data is normal; and a notification unit which transmits, at least to the second GW, a notification that brings the network to a state in which one of a transfer function of the first GW and a transfer function of the second GW gateway is active and the other one of the transfer functions is inactive, when the monitoring unit does not determine that the communication data is normal.