To shorten the warming-up time for an engine by adding one accumulator.

An accumulator 15 is communicated with a refrigerant circulating system 8, liquid phase refrigerant 11 is pressed in the refrigerant circulating system 8 by the accumulator 15 in the cold stop state of an engine 1, and liquid phase refrigerant 11 is filled to the upper space in a condenser 6. While, the liquid phase refrigerant 11 in a liquid cooled jacket 4 is partially evaporated by operational heat of the engine 1 in a state where the engine 1 is operated, pressure is raised, the liquid phase refrigerant 11 in the refrigerant circulating system 8 is pressed and housed in the accumulator 15 by the volume of the liquid phase refrigerant allowed to flow to the condenser 6 after becoming vapor phase refrigerant, and the liquid level Ha of the liquid phase refrigerant 11 is positioned to be lower than a heat radiating part 18 of the condenser 6.