PURPOSE: To increase a polishing speed and to improve accuracy further polishing efficiency by polishing a spherical body with magnetic fluid.

CONSTITUTION: Balls 1, which are workpieces, are interposed between two sheets of lapping disks 3, 4, and the one lapping disk 3 is fixed to the outside by a non-rigid material support 7. The other lapping disk 4 is constituted so as to make rotary motion with a spindle serving as the center. A magnet 5 or electromagnet is arranged on the reverse side to a polishing surface of the lapping disk 3, that is, on the upper external side so as to apply a magnetic field vertically to a polised surface of the ball 1. On the other hand, a magnet 6 or electromagnet is similarly arranged on the reverse side to a polishing surface of the lapping disk 4, that is, on the lower external side to direct magnetic polarity in the same direction to the magnet 5. Further, the magnet 6 is fixed to the lapping disk 4 and preferably not rotated.