An air conditioner may include an outdoor unit including a compressor and an outdoor heat exchanger configured to heat exchange compressed refrigerant; an indoor unit having an air inlet and an air outlet and connected with the outdoor unit through a first pipe through which refrigerant discharged from the compressor flows and a second pipe through which refrigerant discharged from the outdoor heat exchanger flows; a blowing fan disposed in the indoor unit; a main heat exchanger configured to heat exchange air, which flows inside through the air inlet, and connected with the second pipe; a reheat exchanger disposed downstream of the main heat exchanger and connected with the first pipe; and a waste heat exchanger disposed upstream of the main heat exchanger and configured to heat-exchange air, which flows inside through the air inlet, and condensate water, which is produced at the main heat exchanger, with each other. Accordingly, air flowing inside through the air inlet is primarily cooled before exchanging heat through the main heat exchanger, whereby the cooling and dehumidifying performance is improved.