POWER SUPPLY DEVICE

Effectively utilize a capacitor for supplying power to a load when a battery abnormality occurs. A power supply device for connecting to a battery and a load to which power is supplied from the battery includes: a capacitor; a first switch for switching a connection state between the battery and the capacitor; a second switch for switching a connection state between the capacitor and the load; and a control unit for detecting a state of charge of the capacitor and abnormality of the battery. When the abnormality of the battery is not detected, the control unit turns on the first switch and turns off the second switch when the capacitor is not charged, and maintains the first switch on after the capacitor is fully charged.