A power control unit installed on a vehicle including a first power source and a second power source which have respective different voltages, an inverter connected to a rotary device and connected to at least one of the first and second power sources. A converter is connected to the first and second power sources. A casing is formed of an electrically conductive material and has a grounding terminal formed thereon, wherein the inverter and the converter are accommodated within the casing, and are connected to the grounding terminal through said casing.