A refrigerating device is provided whose burden on the environment is small, and in which a high amount of heat can be removed, and in which return of refrigerating device oil to a compressor is good. In the refrigerating device, carbon dioxide is circulated as a refrigerant through a refrigerating circuit in which at least a refrigerant compressor, a heat releasing device, an expansion mechanism and an evaporator are connected in an annular arrangement by refrigerant pipes. The refrigerating device oil used in the compressor has a viscosity at 40° C. of 5 to 300 cSt, a volume specific resistivity of at least 108 &OHgr;·cm, and a pour point of no higher than −30° C. when the carbon dioxide is dissolved to saturation. Organic materials which do not physically and/or chemically change due to high-temperature, high-pressure carbon dioxide are used in the refrigerating circuit. The refrigerating circuit is provided with a device for trapping moisture within the refrigerating circuit.