A refrigeration cycle device comprising: a main refrigerant circuit having a main compressor (21, 22) configured to compress a main refrigerant, a main heat-source-side heat exchanger configured to function as a radiator of the main refrigerant, a main use-side heat exchanger (72a, 72b) configured to function as an evaporator of the main refrigerant, and a main expansion mechanism configured to cause power to be produced by decompressing the main refrigerant that flows between the main heat-source-side heat exchanger and the main use-side heat exchanger, wherein the main refrigerant circuit has a sub-use-side heat exchanger configured to function as a cooler of the main refrigerant that flows between the main expansion mechanism and the main use-side heat exchanger; and the refrigeration cycle device further comprising: a sub-refrigerant circuit having a sub-compressor configured to compress a sub-refrigerant, a sub-heat-source-side heat exchanger configured to function as a radiator of the sub-refrigerant, and the sub-use-side heat exchanger configured to function as an evaporator of the sub-refrigerant and to cool the main refrigerant that flows between the main expansion mechanism and the main use-side heat exchanger, the main refrigerant circuit has a main intermediate-pressure adjusting valve (53, 71a, 71b) between the main expansion mechanism and the main use-side heat exchanger, the refrigeration cycle device characterised in that it further comprises: a control unit configured to control the main intermediate-pressure adjusting valve in accordance with an input power of the sub-refrigerant circuit. a main refrigerant circuit having a main compressor (21, 22) configured to compress a main refrigerant, a main heat-source-side heat exchanger configured to function as a radiator of the main refrigerant, a main use-side heat exchanger (72a, 72b) configured to function as an evaporator of the main refrigerant, and a main expansion mechanism configured to cause power to be produced by decompressing the main refrigerant that flows between the main heat-source-side heat exchanger and the main use-side heat exchanger, wherein the main refrigerant circuit has a sub-use-side heat exchanger configured to function as a cooler of the main refrigerant that flows between the main expansion mechanism and the main use-side heat exchanger; and the refrigeration cycle device further comprising: a sub-refrigerant circuit having a sub-compressor configured to compress a sub-refrigerant, a sub-heat-source-side heat exchanger configured to function as a radiator of the sub-refrigerant, and the sub-use-side heat exchanger configured to function as an evaporator of the sub-refrigerant and to cool the main refrigerant that flows between the main expansion mechanism and the main use-side heat exchanger, the main refrigerant circuit has a main intermediate-pressure adjusting valve (53, 71a, 71b) between the main expansion mechanism and the main use-side heat exchanger, the refrigeration cycle device characterised in that it further comprises: a control unit configured to control the main intermediate-pressure adjusting valve in accordance with an input power of the sub-refrigerant circuit. a sub-refrigerant circuit having a sub-compressor configured to compress a sub-refrigerant, a sub-heat-source-side heat exchanger configured to function as a radiator of the sub-refrigerant, and the sub-use-side heat exchanger configured to function as an evaporator of the sub-refrigerant and to cool the main refrigerant that flows between the main expansion mechanism and the main use-side heat exchanger, the main refrigerant circuit has a main intermediate-pressure adjusting valve (53, 71a, 71b) between the main expansion mechanism and the main use-side heat exchanger, the refrigeration cycle device characterised in that it further comprises: a control unit configured to control the main intermediate-pressure adjusting valve in accordance with an input power of the sub-refrigerant circuit.