An air conditioning system comprising: a refrigeration cycle including a compressor, a reversing valve, a condenser, a pressure reducing device and an evaporator; a thermal storage heat exchanger which is arranged at a lower portion in a thermal storage tank with a thermal storage material filled therein, and whose refrigerant inlet side is smaller than its refrigerant outlet side in terms of heat exchange capability; and a thermal absorption heat exchanger which is arranged at an upper portion in the thermal storage tank in a way to be reverse to the flow direction of a refrigerant in the thermal storage heat exchanger.
