To solve problems that a conventional air-blowing type geothermal heat exchanger utilizing geothermal heat takes moisture in the ground and dust into a room, and then, it is necessary to take measures against it, furthermore, in the case of a conventional cooling fan, a relative humidity becomes high during operation since moisture is taken into a room, and a cool feeling is eliminated since water cannot be evaporated, and furthermore, since the moisture of the evaporated water is taken into the room, mold and bacteria are liable to be generated in the room, thus causing insanitation.

Sanitary air conditioning can be performed while avoiding the intrusion of outside air and moisture into a room by performing in-room cooling by collecting the geothermal heat or performing in-room cooling utilizing the evaporation heat of water by using a heat pump.