A refrigeration apparatus (10A, 10B, 10C, 10D) including: a cooling device which is disposed in a freezer (30, 30a, 30b), and includes a casing (34, 34a, 34b) and a heat exchanger pipe (42, 42a, 42b) disposed in the casing; a refrigerating device (11A, 11B, 11C, 11D) for cooling and liquefying a CO 2 refrigerant; and a refrigerant circuit which is connected to the heat exchanger pipe (42a, 42b) and which is configured to permits the CO 2 refrigerant cooled and liquefied in the refrigerating device to circulate to the heat exchanger pipe (42, 42a, 42b), characterized in that the refrigeration apparatus comprises a sublimation defrost system comprising: a dehumidifier device (38a, 38b) for dehumidifying freezer inner air (c) in the freezer (30a, 30a, 30b); a circulation path forming path connected to an inlet path and an outlet path of the heat exchanger pipe (42, 42a, 42b) such that the circulation path forming path and the heat exchanger pipe forms a CO 2 circulation path; an on-off valve (52a, 52b) disposed in each of the inlet path and the outlet path of the heat exchanger pipe (42, 42a, 42b) and configured to be closed at a time of defrosting so that the CO 2 circulation path becomes a closed circuit; a circulating unit for CO 2 refrigerant, the circulating unit being disposed in the CO 2 circulation path; a first heat exchanger part configured to cause heat exchange between a brine (b) as a first heating medium and the CO 2 refrigerant circulating in the CO 2 circulation path; and a pressure adjusting unit (45a, 45b) for adjusting a pressure of the CO 2 refrigerant circulating in the closed circuit at the time of defrosting wherein the pressure adjusting unit (45a, 45b) includes: a pressure sensor (46a, 46b) for detecting the pressure of the CO 2 refrigerant circulating in the closed circuit; a pressure adjusting valve (48a, 48b) disposed in the outlet path of the heat exchanger pipe; and a control device (47a, 47b) for receiving a detected value from the pressure sensor (46a, 46b), and controlling an opening aperture of the pressure adjusting valve in such a manner that the condensing temperature of the CO 2 refrigerant circulating in the closed circuit becomes equal to or lower than the freezing point of the water vapor in the freezer inner air (c) in the freezer (30, 30a, 30b). a dehumidifier device (38a, 38b) for dehumidifying freezer inner air (c) in the freezer (30a, 30a, 30b); a circulation path forming path connected to an inlet path and an outlet path of the heat exchanger pipe (42, 42a, 42b) such that the circulation path forming path and the heat exchanger pipe forms a CO 2 circulation path; an on-off valve (52a, 52b) disposed in each of the inlet path and the outlet path of the heat exchanger pipe (42, 42a, 42b) and configured to be closed at a time of defrosting so that the CO 2 circulation path becomes a closed circuit; a circulating unit for CO 2 refrigerant, the circulating unit being disposed in the CO 2 circulation path; a first heat exchanger part configured to cause heat exchange between a brine (b) as a first heating medium and the CO 2 refrigerant circulating in the CO 2 circulation path; and a pressure adjusting unit (45a, 45b) for adjusting a pressure of the CO 2 refrigerant circulating in the closed circuit at the time of defrosting wherein the pressure adjusting unit (45a, 45b) includes: a pressure sensor (46a, 46b) for detecting the pressure of the CO 2 refrigerant circulating in the closed circuit; a pressure adjusting valve (48a, 48b) disposed in the outlet path of the heat exchanger pipe; and a control device (47a, 47b) for receiving a detected value from the pressure sensor (46a, 46b), and controlling an opening aperture of the pressure adjusting valve in such a manner that the condensing temperature of the CO 2 refrigerant circulating in the closed circuit becomes equal to or lower than the freezing point of the water vapor in the freezer inner air (c) in the freezer (30, 30a, 30b). a pressure sensor (46a, 46b) for detecting the pressure of the CO 2 refrigerant circulating in the closed circuit; a pressure adjusting valve (48a, 48b) disposed in the outlet path of the heat exchanger pipe; and a control device (47a, 47b) for receiving a detected value from the pressure sensor (46a, 46b), and controlling an opening aperture of the pressure adjusting valve in such a manner that the condensing temperature of the CO 2 refrigerant circulating in the closed circuit becomes equal to or lower than the freezing point of the water vapor in the freezer inner air (c) in the freezer (30, 30a, 30b).