A refrigeration apparatus, comprising: a multistage compression mechanism in which one high-stage-side compression mechanism and a plurality of low-stage-side compression mechanisms (21, 22, 23) are connected in series; switching mechanisms (31, 32, 33) connected to blow-out pipes (101b, 102b, 103b) of the low-stage-side compression mechanisms and configured to switch between a cooling operation cycle and a heating operation cycle; intercoolers (51, 52, 53) configured to cool a refrigerant blown out from the low-stage-side compression mechanisms during the cooling operation cycle; and characterized by further comprising: low-stage-side oil separators (41, 42, 43) placed between the switching mechanisms and the intercoolers, and configured to separate a lubricating oil from the refrigerant blown out from the low-stage-side compression mechanisms during the cooling operation cycle; and a control unit configured to control the multistage compression mechanism and the switching mechanisms, wherein: during the cooling operation cycle, the refrigerant blown out from the low-stage-side compression mechanisms passes through the low-stage-side oil separators and the intercoolers before being sent to the other low-stage-side compression mechanisms or the high-stage-side compression mechanism, during the heating operation cycle, the refrigerant blown out from the low-stage-side compression mechanisms does not pass through the low-stage-side oil separators and the intercoolers before being sent to the other low-stage-side compression mechanisms or the high-stage-side compression mechanism. a multistage compression mechanism in which one high-stage-side compression mechanism and a plurality of low-stage-side compression mechanisms (21, 22, 23) are connected in series; switching mechanisms (31, 32, 33) connected to blow-out pipes (101b, 102b, 103b) of the low-stage-side compression mechanisms and configured to switch between a cooling operation cycle and a heating operation cycle; intercoolers (51, 52, 53) configured to cool a refrigerant blown out from the low-stage-side compression mechanisms during the cooling operation cycle; and characterized by further comprising: low-stage-side oil separators (41, 42, 43) placed between the switching mechanisms and the intercoolers, and configured to separate a lubricating oil from the refrigerant blown out from the low-stage-side compression mechanisms during the cooling operation cycle; and a control unit configured to control the multistage compression mechanism and the switching mechanisms, wherein: during the cooling operation cycle, the refrigerant blown out from the low-stage-side compression mechanisms passes through the low-stage-side oil separators and the intercoolers before being sent to the other low-stage-side compression mechanisms or the high-stage-side compression mechanism, during the heating operation cycle, the refrigerant blown out from the low-stage-side compression mechanisms does not pass through the low-stage-side oil separators and the intercoolers before being sent to the other low-stage-side compression mechanisms or the high-stage-side compression mechanism. low-stage-side oil separators (41, 42, 43) placed between the switching mechanisms and the intercoolers, and configured to separate a lubricating oil from the refrigerant blown out from the low-stage-side compression mechanisms during the cooling operation cycle; and a control unit configured to control the multistage compression mechanism and the switching mechanisms, wherein: during the cooling operation cycle, the refrigerant blown out from the low-stage-side compression mechanisms passes through the low-stage-side oil separators and the intercoolers before being sent to the other low-stage-side compression mechanisms or the high-stage-side compression mechanism, during the heating operation cycle, the refrigerant blown out from the low-stage-side compression mechanisms does not pass through the low-stage-side oil separators and the intercoolers before being sent to the other low-stage-side compression mechanisms or the high-stage-side compression mechanism. during the cooling operation cycle, the refrigerant blown out from the low-stage-side compression mechanisms passes through the low-stage-side oil separators and the intercoolers before being sent to the other low-stage-side compression mechanisms or the high-stage-side compression mechanism, during the heating operation cycle, the refrigerant blown out from the low-stage-side compression mechanisms does not pass through the low-stage-side oil separators and the intercoolers before being sent to the other low-stage-side compression mechanisms or the high-stage-side compression mechanism.