A refrigeration cycle apparatus, comprising: a first compressor for increasing a pressure of a low-pressure refrigerant, which is a refrigerant on a low pressure side, to output an intermediate-pressure refrigerant, which is the refrigerant of an intermediate pressure; a second compressor connected in series to the first compressor, for increasing a pressure of the intermediate-pressure refrigerant to output a high-pressure refrigerant, which is the refrigerant on a high pressure side; a first heat-source-side heat exchanger which is connected in series to the second compressor and through which the high-pressure refrigerant flows; an expander for reducing a pressure of the high-pressure refrigerant to output the low-pressure refrigerant and driving the second compressor by power recovered in the pressure reduction; and a load-side heat exchanger connected in series to the expander, characterized in that a second heat-source-side heat exchanger arranged between the first compressor and the second compressor, an expansion valve arranged in a refrigerant channel portion that branches off a high-pressure refrigerant channel from the first heat source side heat exchanger, and a high and low pressure heat exchanger connected in series to the first heat-source-side heat exchanger, wherein the second heat-source-side heat exchanger cools the intermediate pressure refrigerant, the high and low pressure heat exchanger exchanges heat between the high pressure refrigerant from the first heat source side heat exchanger and a reduced-pressure refrigerant decompressed by the expansion valve, and the expansion valve adjusts a density of the refrigerant flowing in the expander so that the power recovered by the expander and power required by the second compressor match. a first compressor for increasing a pressure of a low-pressure refrigerant, which is a refrigerant on a low pressure side, to output an intermediate-pressure refrigerant, which is the refrigerant of an intermediate pressure; a second compressor connected in series to the first compressor, for increasing a pressure of the intermediate-pressure refrigerant to output a high-pressure refrigerant, which is the refrigerant on a high pressure side; a first heat-source-side heat exchanger which is connected in series to the second compressor and through which the high-pressure refrigerant flows; an expander for reducing a pressure of the high-pressure refrigerant to output the low-pressure refrigerant and driving the second compressor by power recovered in the pressure reduction; and a load-side heat exchanger connected in series to the expander, characterized in that a second heat-source-side heat exchanger arranged between the first compressor and the second compressor, an expansion valve arranged in a refrigerant channel portion that branches off a high-pressure refrigerant channel from the first heat source side heat exchanger, and a high and low pressure heat exchanger connected in series to the first heat-source-side heat exchanger, wherein the second heat-source-side heat exchanger cools the intermediate pressure refrigerant, the high and low pressure heat exchanger exchanges heat between the high pressure refrigerant from the first heat source side heat exchanger and a reduced-pressure refrigerant decompressed by the expansion valve, and the expansion valve adjusts a density of the refrigerant flowing in the expander so that the power recovered by the expander and power required by the second compressor match.