An air conditioner is provided, including an air flow path, a cooling unit disposed in the air flow path that cools air introduced into the air flow path to condense vapor contained in the air, and a humidification unit that humidifies the air and which includes a storage tank for storing water and a heater for heating water in the storage tank. A discharged-water storage unit is also provided, which stores water discharged from the cooling unit and water discharged from the humidification unit, and an exhaust pipe is connected to the storage tank and configured to discharge water in the storage tank to the discharged-water storage unit. An exhaust valve is disposed midway on the exhaust pipe, and an overflow pipe connects the storage tank and a part of the exhaust pipe on the downstream side of the exhaust valve.