An air conditioner including a compressor, an outdoor heat exchanger, an indoor heat exchanger, a switching valve for guiding refrigerant discharged from the compressor to the outdoor heat exchanger during a cooling operation and to the indoor heat exchanger during a heating operation, and an injection module for injecting a portion of the refrigerant discharged from the indoor heat exchanger to the compressor, performing heat exchange between a portion of the refrigerant discharged from the indoor heat exchanger and the refrigerant that moves from the outdoor heat exchanger to the indoor heat exchanger during the cooling operation, and injecting the refrigerant into the compressor.