Abstract: When an infrared ray transmitting and receiving part of an indoor unit receives a command signal for turning on ventilating operation from a wireless remote controller, information of the on-state of the ventilating operation is stored in a first EEPROM of the indoor unit and a second EEPROM of an outdoor unit. By starting up an air blower in a humidifying unit and switching a switchover damper connected to a ventilation pipe, indoor air is discharged to the outside of the room or outdoor air is taken into the room. When the ventilating operation is once stopped by power failure, the ventilating operation resumes on the basis of the information of the on-state of the ventilating operation stored in the first EEPROM after recovery from the power failure. The disadvantage that the ventilating operation stops though no command for turning off the ventilating operation has been received from the operator can be prevented.