PURPOSE: To reduce rotatory loss extremely by constituting a bearing by mutually installing a first member consisting of permanent magnets having different polarity in the diametral direction and a second member composed of an oxide superconductor onto the mutually opposed axial end faces of a rotor and a stator and cooling the bearing and the periphery of a superconducting coil.

CONSTITUTION: Annular permanent magnets 7 having different polarity in the diametral direction are fixed at both axial end faces of a rotor 1. Annular plates 8 formed of an oxide superconductor are fastened onto the internal surfaces of both axial end walls in a fixed casing 5 so as to be oppositely faced to the permanent magnets 7 mounted on the rotor 1. When a coil 4 and the annular plates 8 are cooled by a refrigerant made up of liquid nitrogen and helium gas at that time, these coil and annular plates are brought to a superconductive state, a repulsive gas is generated among the permanent magnets 7 and the annular plates 8, and the rotor 1 is brought to a floated state. The line of magnetic force is pinned by impurities dispersed in the oxide superconductor, and the permanent magnets 7 and the annular plates 8 can be displaced relatively only in the circumferential direction.