A power control unit for electric vehicle includes an inverter for controlling a voltage supplied to a vehicle driving motor from a high-voltage battery. A DC/DC converter reduces the voltage of the high-voltage battery to a voltage capable of charging a low-voltage battery serving as a power supply for an in-vehicle auxiliary machine. The power control unit has a circuit board including first electrical circuit elements that constitute the inverter or the DC/DC converter and second electrical circuit elements together with the first electrical circuit elements. The unit further comprises a heat sink for cooling the first electrical circuit elements, a water pump for circulating a refrigerant in a refrigerant passage of the heat sink, and a water pump control circuit for controlling the operation of the water pump.