A refrigerating apparatus comprises a compressor, a condenser, an expansion valve and a evaporator which are interconnected serially through a pipeline to form a closed circulation circuit. A check valve allowing a coolant flow only toward the condenser is provided between the discharge port of the compressor and the condenser. A hot gas bypass circuit is connected at one end to a junction between the compressor and the check valve and at the other end to a junction between the expansion valve and the evaporator. The check valve serves to prevent backflow of coolant to the hot gas bypass circuit during the hot gas operation mode without hindering the flow of the coolant gas through the closed circulation circuit during the normal refrigerating operation.
