POWER SUPPLY DEVICE, CONTROL METHOD, AND STORAGE MEDIUM

A power supply device includes: a main power supply that supplies power to an electric device; an auxiliary power supply that supplies power to the electric device in response to a failure occurring in the main power supply; and a power supply control unit that performs a first failure determination related to the main power supply and a second failure determination related to the auxiliary power supply. The power supply control unit performs the first failure determination based on a result of first detection processing related to the main power supply, the power supply control unit performs the second failure determination based on a result of second detection processing related to the auxiliary power supply, and a time for which the first detection processing is performed is set to be shorter than a time for which the second detection processing is performed.