POWER CONVERSION DEVICE

A power conversion device has an internal power supply switch configured of an n-channel MOSFET and a bias power supply switch connected in parallel with the internal power supply switch, wherein, when an output voltage of an internal power supply circuit is equal to or greater than a predetermined value when a power supply is started up, the bias power supply switch opens a current path, a step-up power supply circuit steps up and outputs a predetermined voltage based on a power supply start-up signal output by the internal power supply circuit, and the internal power supply switch opens a current path, and when the power supply is stopped, the step-up power supply circuit is stopped based on a stop signal output by the internal power supply circuit and the internal power supply switch closes the current path, and when the output voltage of the internal power supply circuit becomes lower than a predetermined value, the bias power supply switch closes the current path.