PURPOSE: To perform comfortable dehumidifying operation which is not affected by thy outer air flow and atmospheric air temperature by closing first and third switching valves and opening a second switching valve at the time of dehumidifying operation, and opening the third valve when the air temperature in the room becomes a predetermined value or lower.

CONSTITUTION: A first switching valve 5 is closed, a second switching valve 8 is opened, and a third switching valve 21 is closed in a dehumidifying operation. If the outer air flow is much and the atmospheric air temperature is low, heat dissipation amount from an outdoor heat exchanger 9 is remarkably large and when discharge air temperature into the room is lowered, it is detected by indoor diffusing air temperature sensor 22, and compared with a set target room temperature by a temperature comparator 23. If the discharge air temperature is lower by a predetermined value or more than it, a switching valve controller 24 opens the valve 21. Thus, a circuit from a compressor 1 to the valve 8 is composed in parallel with the circuit of a bypass circuit 20, a four-way valve 2 and the exchanger 9, and high temperature, high pressure refrigerant gas discharged from the compressor 1 is distributed in response to the tubular resistances of the two circuits, mostly to pass the circuit 20 and is fed from the valve 8 directly to an indoor heat exchanger 6. Thus, heat radiation amount can be largely reduced to prevent indoor discharge air temperature from lowering.