An air cycle refrigerating/cooling system includes a first heat exchanger for cooling air, a turbine unit that has a compressor for compressing the air and an expansion turbine for adiabatically expanding the air, and a second heat exchanger for cooling the air. A compressor rotor of the compressor and a turbine rotor of the expansion turbine are attached to a common main shaft in the turbine unit in such a manner that the turbine unit drives the compressor rotor with a power generated by the turbine rotor, and the main shaft is rotatably supported by a rolling contact bearing. A part or the entirety of a thrust force applied to the main shaft is supported by an electromagnet, and a pressure equalizing device for equalizing a gas pressure at opposite ends of the rolling contact bearing is provided.