To reduce the damage to an auxiliary bearing when the function of a main magnetic bearing is stopped, and to reduce the cost and time required for maintenance of the auxiliary bearing by applying a magnetic field to the auxiliary bearing in its radial direction.

A magnetic bearing M includes an auxiliary bearing B as a backup in the case where abnormality occurs in a main magnetic bearing 2. The auxiliary bearing B is provided with an inner ring Ba which is formed of a magnetic body and through which a magnetic field H1 in the radial direction of the shaft 4 to be rotatable in the same direction as the shaft 4, an outer ring Bb fixed to a casing C or the like, a rolling element Bc, and a sleeve B1 fitted to the shaft 4. Button-like permanent magnets B2 are embedded in plural portions in the circumferential direction of the shaft 4 in the interior of the sleeve 1. When the shaft 4 is rotated, the inner ring Ba is steadily rotated at a rather slow speed with a fixed slippage to the shaft 4 by the interaction of the magnetic field. Thus, when the function of the main magnetic bearing 2 is stopped, force due to sudden acceleration is not applied to the rolling element Bc or the like so as to reduce damage to the auxiliary bearing B.