Refrigeration cycle apparatus and control method

It is an object of the present invention to overcome the problems concerning control in the adjustment of an opening of a decompressor, to reduce the apparatus in size, to enhance the reliability of the apparatus, and to enhance the COP. A refrigeration cycle apparatus which uses a refrigerant that can be brought into a supercritical state on a high pressure side, which includes at least a compressor 21, a radiator 22, an internal heat exchanger 27, a decompressor 23 and an evaporator 25, and which does not have a refrigerant amount adjusting means, the refrigeration cycle apparatus comprising discharge temperature detecting means 30 which detects a temperature of the refrigerant from the compressor 21 and the radiator 22, and a first decompressor operation device 31 which operates an opening of the decompressor 23 based on an output value of the discharge temperature detecting means 30.