A refrigeration cycle apparatus (1A, 1B), comprising: a refrigerant circuit including a compressor, a condenser, a subcooling heat exchanger, a main expansion valve capable of adjusting an opening thereof, and an evaporator that are connected circularly; a bypass passage that is branched from the refrigerant circuit between the condenser and the subcooling heat exchanger or between the subcooling heat exchanger and the main expansion valve, and extends through the subcooling heat exchanger to join to the refrigerant circuit between the evaporator and the compressor; and a bypass expansion valve provided in the bypass passage upstream of the subcooling heat exchanger, the bypass expansion valve being capable of adjusting an opening thereof; a first temperature sensor for detecting a temperature of a refrigerant that has flowed out of the subcooling heat exchanger in the bypass passage; a second temperature sensor for detecting a temperature of the refrigerant that has flowed out of the evaporator in the refrigerant circuit; and characterized by comprising a controller for controlling the opening of the bypass expansion valve so that the temperature detected by the first temperature sensor conforms to a saturation temperature at a pressure of the refrigerant to be drawn into the compressor (21, and a degree of superheat at an outlet of the evaporator calculated based on the temperature detected by the second temperature sensor is equal to or lower than a predetermined degree of superheat, wherein the controller reduces the opening of the bypass expansion valve when the degree of superheat at the outlet of the evaporator is higher than the predetermined degree of superheat. a refrigerant circuit including a compressor, a condenser, a subcooling heat exchanger, a main expansion valve capable of adjusting an opening thereof, and an evaporator that are connected circularly; a bypass passage that is branched from the refrigerant circuit between the condenser and the subcooling heat exchanger or between the subcooling heat exchanger and the main expansion valve, and extends through the subcooling heat exchanger to join to the refrigerant circuit between the evaporator and the compressor; and a bypass expansion valve provided in the bypass passage upstream of the subcooling heat exchanger, the bypass expansion valve being capable of adjusting an opening thereof; a first temperature sensor for detecting a temperature of a refrigerant that has flowed out of the subcooling heat exchanger in the bypass passage; a second temperature sensor for detecting a temperature of the refrigerant that has flowed out of the evaporator in the refrigerant circuit; and characterized by comprising a controller for controlling the opening of the bypass expansion valve so that the temperature detected by the first temperature sensor conforms to a saturation temperature at a pressure of the refrigerant to be drawn into the compressor (21, and a degree of superheat at an outlet of the evaporator calculated based on the temperature detected by the second temperature sensor is equal to or lower than a predetermined degree of superheat, wherein the controller reduces the opening of the bypass expansion valve when the degree of superheat at the outlet of the evaporator is higher than the predetermined degree of superheat.