PURPOSE: To provide a polishing method in use of a globular abradant that is hard to produce any chip and its separation from a steel ball for a pinball machine is surely performed by a small-scale device and also efficient polishing is achievable.

CONSTITUTION: A plastic abradant if formed into a sphere being larger in diameter than a steel ball (for a pinball game) 2, and this spherical abradant 1 is stirred up with the steel ball 1 in a polishing cylinder 6, whereby the steel ball 2 is polished and, after polishing, when the spherical abradant 1 is separated from the steel ball 2 by a screen 10, each clearance of this screen 10 is made wider than the ball 2 but narrower than the spherical abradant 1 the other way and thereby the steel ball 2 being large in specific gravity is made so as to be dropped from the screen 10. In succession, the spherical abradant 1 is rolled on the screen 10 and formed so as to be transferred to the polishing cylinder 6 again through a distribution passage.