Heat exchangers of a refrigerant circuit 50 are constructed of a first adsorption heat exchanger 51 and a second adsorption heat exchanger 52, both of which have an adsorbent supported thereon, and are constructed so as to be switched into an evaporator and a condenser. An air passage 60 is constructed so as to be switched into states in which air flowing from the outside of a room to the inside of the room and air flowing from the inside of the room to the outside of the room flow through either of the first adsorption heat exchanger 51 and the second adsorption heat exchanger 52. A dehumidifying operation mode and a humidifying operation mode can be performed by switching the flow of refrigerant and the flow of air at specified intervals, a cooling operation mode and a heating operation mode can be performed without switching the flow of refrigerant and the flow of air, and an ventilating operation mode can be performed by flowing air through the air passage 60 in a state where the refrigerant circuit 50 is stopped.