An air-conditioning apparatus includes an outside-air processing device including a total heat exchanger exchanging heat between outdoor air and return air, and blowing out the outdoor air from a supply-air outlet port into a room as supply air, an indoor unit including an indoor heat exchanger exchanging heat between the return air and refrigerant, and blowing out the return air from an indoor outlet port as indoor outlet air, a joining unit connecting the supply-air outlet port and the indoor outlet port to join the supply air and the indoor outlet air, an opening-closing unit arranged in the joining unit and opening and closing the joining unit, a supply-air temperature detecting unit detecting a supply-air temperature of the supply air, an indoor outlet temperature detecting unit detecting an indoor outlet temperature of the indoor outlet air, and a control unit controlling an operation of the opening-closing unit based on the supply-air temperature and the indoor outlet temperature.