An in-vehicle instrument control device, that controls a power source of a plurality of in-vehicle instruments operated by power from the power source provided in a vehicle, includes a plurality of operation units to operate the respective in-vehicle instruments; and a plurality of power source control units that are each provided between the operation unit and the power source, and the in-vehicle instrument, and each supply the power from the power source to the in-vehicle instrument when a predetermined operation signal is inputted from the operation unit.