An air-conditioning apparatus includes an air-conditioner and an oxygen ratio increasing device. The air-conditioner has an indoor unit having an indoor heat exchanger and arranged in a room to be air-conditioned, and an outdoor unit having an outdoor heat exchanger and arranged outdoors. These units are connected to each other through a coolant pipe. The increasing device has an oxygen ratio increasing mechanism for producing oxygen-ratio increased air having a high oxygen concentration, and an air supply pipe for supplying the produced oxygen-ratio increased air into the room. The mechanism is arranged in the outdoor unit, and includes an adsorbing material for adsorbing nitrogen in air to produce the oxygen-ratio increased air and an air compressor for supplying air to the air supply pipe through the adsorbing material.