To provide an eccentric disc polishing machine braking force of which is automatically restricted by an opening and a valve type flap provided on an abrasion ring.

The eccentric disc polishing machine 10 furnished with a cylindrical casing 12 has an edge 16 a casing lower part region of which is on the end surface side, a polishing disc free to rotate is arranged adjacent to it in the axial direction, a ring type braking means positioned between the polishing disc 20 and the edge is arranged, this braking means 30 supported on the polishing disc 20 by an elastic lip 32 works braking force on the polishing disc 20, in this case, the braking means 30 further closes a suction chamber by sealing it outward in the inside of the casing in a region of the polishing disc, and in this case, the braking means 30 has an opening free to open and close by the valve type flap and useful for ventilation of the suction chamber.