To provide a spindle motor which significantly improves the non- repetitive run-out(NRRO), even if it is in a high-speed revolving condition.

The spindle motor BB, which has a shaft 4 tightly fixed to the revolving center of a rotor hub 12A; a bearing holder 6A comprising a non-magnetic member disposed upright on a motor base 5; and sleeve bearings 9A and 9B which rotatably support the shaft 4 inserted in the bearing holder 6A, has a semicircular or arch-like attraction magnet 16, which is fitted and fixed to the outer periphery 6Aa of the holder 6A situated in the mid-position between the bearings 9A and 9B. The magnet 16 applies side-pressure to the bearings 9A and 9B, respectively, by magnetically attracting the shaft 4 within the holder 6A in the radial direction through the holder 6A.