PURPOSE: To attempt both high efficiency and high precision of work with feasibility of simultaneous machining on both plane surfaces and side surface of a workpiece, by employing a pair of rollers arranged at an interval narrower than the diameter of the workpiece to machine the side surface thereof and a pair of rotary discs for machining parallel plane surfaces thereof in a direction suitable for pushing the workpiece toward said rollers.

CONSTITUTION: When rotary discs 7, 8 are turned in directions (a) and (b) respectively, a glass plate 1 moves in C direction along a vertical bisector L due to the frictional force given from polishing cloth 11, 12 and reaches a position where it touches rollers 2, 3 and a supporting blade 13. Therefore, if the rollers 2, 3 are turned in directions (d) and (e) respectively, the glass plate 1 makes self-rotation in (f) direction. Hereat, the frictional force between the glass plate 1 and roller 3 is larger than that between the same plate 1 and roller 2, consequently the glass plate 1 makes no slip against the roller 3. Therefore, slipping takes place between polishing cloth 6 and the side surface of the glass plate 1 by setting the numbers of revolution of roller 2 and 3 respectively. Thus, polishing of the side surface can be carried out with high efficiency and high precision simultaneously with polishing of parallel planes with polishing cloth 11, and 12 by suppling polishing agent.