A refrigeration cycle apparatus comprising: a refrigerant circuit including a compressor, a condenser (5, 7), a pressure-reducing device, and an evaporator (5, 7); and a controller configured to control the refrigerant circuit, wherein refrigerant circulating through the refrigerant circuit is refrigerant containing propane or propylene, the evaporator (5, 7) has a heat transfer pipe in which refrigerant flows, a refrigerant port temperature sensor (22, 23) for detecting temperature of refrigerant is provided at an entrance port of the evaporator (5, 7), an inner temperature sensor (24, 25) for detecting temperature of refrigerant is provided in the heat transfer pipe of the evaporator (5, 7), characterized in that, in the evaporator (5, 7), a length of the heat transfer pipe between the entrance port of the evaporator (5, 7) and the inner temperature sensor (24, 25) is greater than or equal to 66% of a length of the heat transfer pipe between the entrance port of the evaporator (5, 7) and an exit port of the evaporator (5, 7), and less than or equal to 88% of the length of the heat transfer pipe between the entrance port and the exit port, the controller configured to set a degree of superheat of refrigerant at an entrance port of the compressor to be a value greater than or equal to 10 degrees by controlling the opening degree of the pressure-reducing device, and the controller configured to control the opening degree of the pressure-reducing device so that the temperature of refrigerant detected by the inner temperature sensor (24, 25) is higher than the temperature of refrigerant detected by the refrigerant port temperature sensor (22, 23). a refrigerant circuit including a compressor, a condenser (5, 7), a pressure-reducing device, and an evaporator (5, 7); and a compressor, a condenser (5, 7), a pressure-reducing device, and an evaporator (5, 7); and a controller configured to control the refrigerant circuit, wherein refrigerant circulating through the refrigerant circuit is refrigerant containing propane or propylene, the evaporator (5, 7) has a heat transfer pipe in which refrigerant flows, a refrigerant port temperature sensor (22, 23) for detecting temperature of refrigerant is provided at an entrance port of the evaporator (5, 7), an inner temperature sensor (24, 25) for detecting temperature of refrigerant is provided in the heat transfer pipe of the evaporator (5, 7), characterized in that, in the evaporator (5, 7), a length of the heat transfer pipe between the entrance port of the evaporator (5, 7) and the inner temperature sensor (24, 25) is greater than or equal to 66% of a length of the heat transfer pipe between the entrance port of the evaporator (5, 7) and an exit port of the evaporator (5, 7), and less than or equal to 88% of the length of the heat transfer pipe between the entrance port and the exit port, the controller configured to set a degree of superheat of refrigerant at an entrance port of the compressor to be a value greater than or equal to 10 degrees by controlling the opening degree of the pressure-reducing device, and the controller configured to control the opening degree of the pressure-reducing device so that the temperature of refrigerant detected by the inner temperature sensor (24, 25) is higher than the temperature of refrigerant detected by the refrigerant port temperature sensor (22, 23).