A cooling device utilizes a vapor compression refrigeration cycle including a compressor, a condenser, a receiver, an expansion valve, an evaporator, and an accumulator to cool a heat source with a coolant. The receiver separates the coolant having been subjected to heat exchange by the condenser into gas and liquid. The accumulator separates the coolant having been subjected to heat exchange by the evaporator into gas and liquid. The cooling device opens a switch valve capable of bringing the receiver and the accumulator into communication with each other to move the coolant liquid in the accumulator to the receiver. The cooling device restores the pressure difference between the receiver and the accumulator after the movement of the coolant liquid to the pressure difference before the movement of the coolant liquid by a pressure regulating unit.