To provide a power supply device for a vehicle which continues operation judging that a power supply has recovered when an input voltage is normal, even if the waveform of the input voltage is distorted when recovering from a section.

According to a DC voltage obtained by rectification due to a diode rectifying circuit 7 of an input part 3, AC output is obtained by a DC/AC converter 10, and DC output is obtained by a DC/DC converter 9, thus controlling the DC/DC converter 9 and DC/AC converter 10 at a high speed, and stabilizing an output voltage, when a voltage is applied to a section without detecting the section.