VEHICLE POWER SOURCE DEVICE

A power supply device for vehicles is disclosed, which device includes a backup unit to the power supply as an auxiliary power supply employing a capacitor unit formed of plural capacitors. The auxiliary power supply includes a power supply section allowing the capacitor unit to power an electronic controller, and a compulsory operating section for operating the power supply section. An operating status of the power supply section is monitored even when a battery operates normally, so that the power supply device for vehicles with higher reliability and improved safety is obtainable.