A refrigeration cycle apparatus comprising: a main circuit in which a compressor, a condenser, a main expansion valve, and an evaporator are connected in a circle, the main circuit being configured to circulate refrigerant having a higher boiling point than R407C therethrough; a bypass (40, 41) configured to combine a flow of part of refrigerant discharged from the compressor and a flow of refrigerant flowing out of the condenser into a combined flow, and allowing the combined flow to flow into a suction side of the compressor; a negative pressure regulating valve (7, 9) configured to regulate a flow rate in the bypass (40, 41); a compressor suction pressure sensor at a suction side of the compressor; and a negative pressure prevention control unit (20a, 20A) configured to perform a negative pressure prevention operation of controlling the negative pressure regulating valve (7, 9) to prevent the suction pressure of the compressor from becoming smaller than atmospheric pressure, wherein the bypass includes a discharged gas bypass configured to bypass part of refrigerant discharged from the compressor to a suction side, and a suction bypass configured to combine a flow of refrigerant flowing out of the condenser into a flow in the discharged gas bypass, and allowing the flow to flow into the suction side of the compressor, wherein the negative pressure regulating valve is a discharged gas bypass valve configured to regulate a flow rate in the discharged gas bypass, and wherein during the negative pressure prevention operation, the negative pressure prevention control unit (20a, 20A) is configured to close the main expansion valve and also regulate an opening degree of the discharged gas bypass valve so that the suction pressure becomes a second setting value set in advance. a main circuit in which a compressor, a condenser, a main expansion valve, and an evaporator are connected in a circle, the main circuit being configured to circulate refrigerant having a higher boiling point than R407C therethrough; a bypass (40, 41) configured to combine a flow of part of refrigerant discharged from the compressor and a flow of refrigerant flowing out of the condenser into a combined flow, and allowing the combined flow to flow into a suction side of the compressor; a negative pressure regulating valve (7, 9) configured to regulate a flow rate in the bypass (40, 41); a compressor suction pressure sensor at a suction side of the compressor; and a negative pressure prevention control unit (20a, 20A) configured to perform a negative pressure prevention operation of controlling the negative pressure regulating valve (7, 9) to prevent the suction pressure of the compressor from becoming smaller than atmospheric pressure, wherein the bypass includes a discharged gas bypass configured to bypass part of refrigerant discharged from the compressor to a suction side, and a suction bypass configured to combine a flow of refrigerant flowing out of the condenser into a flow in the discharged gas bypass, and allowing the flow to flow into the suction side of the compressor, wherein the negative pressure regulating valve is a discharged gas bypass valve configured to regulate a flow rate in the discharged gas bypass, and wherein during the negative pressure prevention operation, the negative pressure prevention control unit (20a, 20A) is configured to close the main expansion valve and also regulate an opening degree of the discharged gas bypass valve so that the suction pressure becomes a second setting value set in advance.