An AC/DC power supply device for operating a refrigerator compressor by switching over the AC operation mode in which the compressor is operated from AC power source and the DC operation mode in which the compressor is operated from DC power source through an inverter circuit, wherein a thermostat is constructed so as to be connected to a circuit for supplying DC voltage to the inverter circuit in the DC operation mode, and a switching section is constructed so that high potential points including the potential of the AC power source and low potential points including the potential of the DC power source do not face each other in close vicinity to prevent the AC power voltage from being unwantedly applied to the low voltage side.