To solve the dispersion in magnetic field strength within a vessel and to uniformly polish all parts of a material to be polished by horizontally installing a cylindrical polishing vessel within a hollow cylindrical stator for generating a rotating magnetic field with central axis horizontally placed, and gently rotating this device.

A stator 1 having a number of windings 2 is provided, and a polishing vessel 3 is installed into the stator 1 instead of a rotor in a motor. The polishing vessel 3 preferably has a diameter as large as possible within the range never making contact with the windings 2. A material to be polished 4, a number of magnetic small pieces 5 and an abrasive liquid 6 are put in the polishing vessel 3. Two rotating shafts 9 extended from the circular surfaces 8 of the polishing vessel 3 are easily rotatably supported by rollers 10. The rotating shafts 9 have flanges 11 at the ends, and the flanges 11 are fixed to the circular surfaces of the polishing vessel 3 by screws 12 through packings. According to this, the whole polishing vessel 3 is rotatably journalled to the rollers 10.