AIR CONDITIONER

PROBLEM TO BE SOLVED: To provide an air conditioner with a start-up made quicker in a heating operation.SOLUTION: The air conditioner includes: a heat storage tank having a regenerative heat exchanger and a heat storage material that stores heat generated by a compressor, both installed in the tank; a heat storage bypass circuit connecting a path between an indoor heat exchanger and an expansion valve to a path between a four-way valve and a suction port of the compressor; and a defrosting bypass circuit connecting a path between the expansion valve and an outdoor heat exchanger to a path between a discharge port of the compressor and the four-way valve. The regenerative heat exchanger and a heat storage two-way valve are laid in the heat storage bypass circuit, while a defrosting two-way valve is laid in the defrosting bypass circuit. When a start temperature of defrosting is detected by a detecting means for an entrance temperature of the indoor heat exchanger, the air conditioner opens the heat storage two-way valve and the defrosting two-way valve to carry out a defrosting operation while continuing a heating operation. After the defrosting operation is completed, the air conditioner sets a frequency of the compressor to the frequency of the compressor before starting the defrosting operation.