PURPOSE: To easily carry out a uniform polishing treatment by constituting a polishing surface section for pulverizing and polishing a feed coarse material by bringing nearly the entire part of the opposite surface parts of a rotary polishing member and a static polishing member deep in the depth in a longitudinal direction into contact with each other at the entire circum ference of a cylindrical shape.

CONSTITUTION: A hollow cylindrical rotary barrel 21 is freely rotatably held upright by a hollow shaft cylinder 23 in a rotary cylindrical barrel section 20 rotationally driven by a drive means 40. A static cylindrical barrel section 30 which faces this rotary cylindrical barrel section 20 in a concentric form and is held vertically movably by a machine body frame 10. The rotary polishing member 22 and the static polishing member 32 are mounted at the each other's opposite surface parts of the cylindrical barrel sections 20, 30 so as to form polishing surface sections M sliding with each other by coming into surface-to-surface contact with each other. The static cylindrical barrel section 30 is provided with a cylindrical hollow axial central section 31 and the static polishing member 32 mounted at this axial central section 31 is held pressurized contactably or spatially with or from the rotary polishing member 22 by a sliding holding means 12. In addition, a convergent coarse material feed ring groove 33 is formed to such a cylindrical shape as to be formed at the top end in correspondence to the cylindrical barrel section 20.