PURPOSE: To provide sufficient air-conditioning ability without generating dewing on window inner surfaces at the time of heating operation under the environment of a freezing cycle being hard to be operated.

CONSTITUTION: A ventilation passage 1 where inner air is circulated is provided, and an evaporator 5 of a freezing cycle is provided in this ventilation passage 1, and a relay heat exchanger 15 is provided outside the ventilation passage 1, and cooling devices 16, 17, 18 to cool this heat exchanger 15 by means of outer air are provided, and also refrigerant circulation devices 19, 20 to circulate a refrigerant are provided at a mutual space between the evaporator 5 and the relay that exchanger 15. As a result, the whole of the evaporator 5 and the relay heat exchanger 15 is operated as a separation type heat pipe heat exchanger which makes the heat exchanger 15 a radiation portion and the evaporator 5 an endothermic portion, and by the movement of heat obtained by means of the heat pipe heat exchanger without operating the freezing cycle, moisture contained in inner air is removed by utilizing low temperature outer air.