A refrigeration cycle device comprising: a refrigerant circuit including a first compressor , a second compressor , a heat-source-side heat exchanger , an expansion mechanism , and a use-side heat exchanger , and capable of performing a single-stage compression operation in which one of the first compressor and the second compressor is driven and the other is stopped, and a two-stage compression operation in which both the first compressor and the second compressor are driven; and a control unit configured to control the refrigerant circuit so that, of the single-stage compression operation and the two-stage compression operation, an operation with a higher compression efficiency is performed, characterized in that the control unit is configured to control the refrigerant circuit so that the single-stage compression operation is performed if a required capacity (Q) of the refrigerant circuit is below a predetermined capacity threshold (Qth), and control the refrigerant circuit so that the two-stage compression operation is performed if the required capacity (Q) of the refrigerant circuit is not below the capacity threshold (Qth), and the capacity threshold (Qth) is a value that changes in accordance with a physical quantity (X) correlated with a difference between a high pressure and a low pressure in the refrigerant circuit , and corresponds to the required capacity (Q) of the refrigerant circuit at a boundary at which a compression efficiency (η2) in the two-stage compression operation becomes higher than a compression efficiency (η1) in the single-stage compression operation under a condition that the physical quantity (X) is a physical quantity (X) corresponding to the capacity threshold (Qth). a refrigerant circuit including a first compressor , a second compressor , a heat-source-side heat exchanger , an expansion mechanism , and a use-side heat exchanger , and capable of performing a single-stage compression operation in which one of the first compressor and the second compressor is driven and the other is stopped, and a two-stage compression operation in which both the first compressor and the second compressor are driven; and a control unit configured to control the refrigerant circuit so that, of the single-stage compression operation and the two-stage compression operation, an operation with a higher compression efficiency is performed, characterized in that the control unit is configured to control the refrigerant circuit so that the single-stage compression operation is performed if a required capacity (Q) of the refrigerant circuit is below a predetermined capacity threshold (Qth), and control the refrigerant circuit so that the two-stage compression operation is performed if the required capacity (Q) of the refrigerant circuit is not below the capacity threshold (Qth), and the capacity threshold (Qth) is a value that changes in accordance with a physical quantity (X) correlated with a difference between a high pressure and a low pressure in the refrigerant circuit , and corresponds to the required capacity (Q) of the refrigerant circuit at a boundary at which a compression efficiency (η2) in the two-stage compression operation becomes higher than a compression efficiency (η1) in the single-stage compression operation under a condition that the physical quantity (X) is a physical quantity (X) corresponding to the capacity threshold (Qth). <EOS>