An air conditioner according to the present invention prevents freezing of an outdoor heat exchanger in heating operation. A refrigeration cycle is formed by sequentially connecting a compressor 1, a four-way valve 2, an indoor heat exchanger 3, a pressure reducing device 4, and an outdoor heat exchanger 5. In the refrigeration cycle, a high-temperature and high-pressure refrigerant compressed by the compressor 1 flows through a receiver tank 6 before supplied for indoor heating. The receiver tank 6 is placed in the outdoor heat exchanger 5, and thus heat from the receiver tank 6 through which the high-temperature and high-pressure refrigerant flows can be used to prevent freezing of a fin or a tube 10 in the outdoor heat exchanger 5, thereby ensuring heating performance.