PURPOSE: To prevent the generation of vibration during grinding operation by providing holding-bodies for holding workpieces within faces spaced a specified distance apart and opposed each other with grinding medium fluid held between the faces, and driving the holding bodies to move the workpieces within the faces at a specified speed.

CONSTITUTION: When rotary plates 25a and 2b on whose side surfaces plural workpieces 1 are mounted by means of workpiece-holding plates 2 are driven to rotate by an electric motor 21, flows of a grinding medium fluid 4 along the tangential direction of the rotary plates 25a, 25b are produced on the outer peripheries of the rotary plates 25a, 25b. At the portion where the rotary plates 25a and 25b are close to each other and spaced a specified distance apart, the flows of the grinding medium fluid 4 run in the opposite directions, so that these flows of the grinding medium fluid 4 collide with each other, and at this time, the grinding medium fluid 4 strikes the workpieces 1, thereby grinding the workpieces 1. In this case, since the grinding medium fluid 4 uniformly strikes each workpiece 1, each workpiece 1 is uniformly and specularly ground. This method does not utilize the fluid-bearing condition, so that the vibration due to this condition can be eliminated.