A refrigeration device (1, 101, 201), comprising: a main refrigerant circuit (10, 110, 210) having a compressor, a heat source side heat exchanger, and a user side heat exchanger; an auxiliary refrigerant circuit (42, 242) arranged between the compressor of the main refrigerant circuit and the user side heat exchanger, and which can return a portion of the refrigerant that is compressed in the compressor and sent to the user side heat exchanger to the main refrigerant circuit after being condensed, wherein the auxiliary refrigerant circuit (42, 242) comprises a branching circuit that serves to branch a portion of refrigerant compressed in the compressor and sent to the user side heat exchanger from the main refrigerant circuit (10, 110, 210), a condenser (42b, 242b) that can condense the branched refrigerant, and a junction circuit that can return the condensed refrigerant to the main refrigerant circuit; and a four way switching valve for switching the direction of the refrigerant flow when switching between cooling operations and heating operations; characterized in that the auxiliary refrigerant circuit (42, 242) further comprises a bypass circuit that can bypass the condenser (42b, 242b) and propagate refrigerant from the compressor to the user side heat exchanger; and the main refrigerant circuit (10, 110, 210) further comprises a check mechanism, which is provided between a connector that connects the branching circuit to the main refrigerant circuit and a connector that connects the junction circuit to the main refrigerant circuit, and which allows only the flow of refrigerant from the user side heat exchanger to the compressor. a main refrigerant circuit (10, 110, 210) having a compressor, a heat source side heat exchanger, and a user side heat exchanger; an auxiliary refrigerant circuit (42, 242) arranged between the compressor of the main refrigerant circuit and the user side heat exchanger, and which can return a portion of the refrigerant that is compressed in the compressor and sent to the user side heat exchanger to the main refrigerant circuit after being condensed, wherein the auxiliary refrigerant circuit (42, 242) comprises a branching circuit that serves to branch a portion of refrigerant compressed in the compressor and sent to the user side heat exchanger from the main refrigerant circuit (10, 110, 210), a condenser (42b, 242b) that can condense the branched refrigerant, and a junction circuit that can return the condensed refrigerant to the main refrigerant circuit; and a four way switching valve for switching the direction of the refrigerant flow when switching between cooling operations and heating operations; characterized in that the auxiliary refrigerant circuit (42, 242) further comprises a bypass circuit that can bypass the condenser (42b, 242b) and propagate refrigerant from the compressor to the user side heat exchanger; and the main refrigerant circuit (10, 110, 210) further comprises a check mechanism, which is provided between a connector that connects the branching circuit to the main refrigerant circuit and a connector that connects the junction circuit to the main refrigerant circuit, and which allows only the flow of refrigerant from the user side heat exchanger to the compressor.