A refrigeration apparatus that operates in a supercritical range, the refrigeration apparatus comprising: a compression mechanism (2, 202) having a plurality of compression elements and configured so that refrigerant discharged from a first-stage compression element of the plurality of compression elements is sequentially compressed by a second-stage compression element; a heat source-side heat exchanger in which air is used as a heat source and which functions as a cooler or heater of refrigerant; an expansion mechanism (5, 5a, 5b, 5c, 5d) for depressurizing the refrigerant; a usage-side heat exchanger which functions as a heater or cooler of refrigerant; a switching mechanism for switching between a cooling operation state wherein the refrigerant is sequentially circulated through the compression mechanism, the heat source-side heat exchanger, the expansion mechanism, and the usage-side heat exchanger; and a heating operation state wherein the refrigerant is sequentially circulated through the compression mechanism, the usage-side heat exchanger, the expansion mechanism, and the heat source-side heat exchanger; characterized by an intercooler integrated with the heat source-side heat exchanger and having air as a heat source, the intercooler provided to an intermediate refrigerant tube for drawing refrigerant discharged from the first-stage compression element into the second-stage compression element, and functioning as a cooler of the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element; an intercooler bypass tube connected to the intermediate refrigerant tube so as to bypass the intercooler; and a second-stage injection tube for branching off and returning the refrigerant cooled in the heat source-side heat exchanger or the usage-side heat exchanger to the second-stage compression element, the second-stage injection tube having an opening degree-controllable second-stage injection valve, wherein when the switching mechanism is switched to the cooling operation state to allow refrigerant to flow to the heat source-side heat exchanger whereby a reverse cycle defrosting operation for defrosting the heat source-side heat exchanger is performed, the refrigerant is caused to flow to the heat source-side heat exchanger, the intercooler and the second-stage injection tube, and after defrosting of the intercooler is detected as being complete, the intercooler bypass tube is used so as to ensure that the refrigerant does not flow to the intercooler and so as to control that the opening degree of the second-stage injection valve is increased. a compression mechanism (2, 202) having a plurality of compression elements and configured so that refrigerant discharged from a first-stage compression element of the plurality of compression elements is sequentially compressed by a second-stage compression element; a heat source-side heat exchanger in which air is used as a heat source and which functions as a cooler or heater of refrigerant; an expansion mechanism (5, 5a, 5b, 5c, 5d) for depressurizing the refrigerant; a usage-side heat exchanger which functions as a heater or cooler of refrigerant; a switching mechanism for switching between a cooling operation state wherein the refrigerant is sequentially circulated through the compression mechanism, the heat source-side heat exchanger, the expansion mechanism, and the usage-side heat exchanger; and a heating operation state wherein the refrigerant is sequentially circulated through the compression mechanism, the usage-side heat exchanger, the expansion mechanism, and the heat source-side heat exchanger; characterized by an intercooler integrated with the heat source-side heat exchanger and having air as a heat source, the intercooler provided to an intermediate refrigerant tube for drawing refrigerant discharged from the first-stage compression element into the second-stage compression element, and functioning as a cooler of the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element; an intercooler bypass tube connected to the intermediate refrigerant tube so as to bypass the intercooler; and a second-stage injection tube for branching off and returning the refrigerant cooled in the heat source-side heat exchanger or the usage-side heat exchanger to the second-stage compression element, the second-stage injection tube having an opening degree-controllable second-stage injection valve, wherein when the switching mechanism is switched to the cooling operation state to allow refrigerant to flow to the heat source-side heat exchanger whereby a reverse cycle defrosting operation for defrosting the heat source-side heat exchanger is performed, the refrigerant is caused to flow to the heat source-side heat exchanger, the intercooler and the second-stage injection tube, and after defrosting of the intercooler is detected as being complete, the intercooler bypass tube is used so as to ensure that the refrigerant does not flow to the intercooler and so as to control that the opening degree of the second-stage injection valve is increased.