ELECTRIC POWER SUPPLY DEVICE

An electric power supply device includes first and second batteries respectively supplying electric power to a plurality of load instruments mounted on a vehicle, an electric power generator capable of charging the first battery and the second battery by regenerative electric power generation, and control means for controlling the electric power generator so that a charging electric power amount of at least one of the first battery and the second battery based on the regenerative electric power generation is suppressed in a case where at least one of a high-load instrument and a backup target instrument is present among the plurality of load instruments and the electric power generator is performing the regenerative electric power generation during the deceleration of the vehicle.