To improve defrosting performance while suppressing lowering of an utilization-side temperature in performing a reverse cycle defrosting operation, in a refrigerating device having a refrigerant circuit constituted to switch between a cooling operation and a heating operation, and performing a multiple stage compression type refrigerating cycle by using a refrigerant acting in a supercritical region.

An air conditioner 1 uses carbon dioxide as the refrigerant and is provided with a two-stage compression type compression mechanism 2, a heat source-side heat exchanger 4, an expansion mechanism 5, a utilization-side heat exchanger 6, a switching mechanism 3, and a first rear stage-side injection pipe 18c. The air conditioner 1 is adapted such that, at least in an initial stage of a reverse cycle defrosting operation which defrosts the heat source-side heat exchanger 4 by switching the switching mechanism 3 to a cooling operation state, the refrigerant does not return to a rear stage-side compression element 2d through the first rear stage-side injection pipe 18c.