PURPOSE: To improve the coefficient of friction resistance and the cooling efficiency of grinding grains, by a method wherein, in a state in which two inner and outer grinding stones rotated in a reverse direction to each other are arranged in a radial manner, the working surface of each grinding stone is moved and atmospheric pressure washing is applied on the working surface.

CONSTITUTION: The one grinding stone table 4 is rotated clockwisely through the drive of a motor C, and the other grinding stone table 41 is rotated counterclockwisely. A centrifugal force is exerted in a clockwise direction on radially-arranged grinding stones 3 radially arranged on the grinding stone table 4, and the working surface thereof is moved. Further, a centripetal force is exerted on grinding stones 31, a radially arranged on the grinding stone table 41, through rotation, and the working surface thereof is moved. The plane part of a cutter D supported on an outer or an inner rule 1 or 2 is polished by means of the working surface. In this case, atmospheric pressure washing is applied on the working surface, and atmospheric-pressure-washed chips are discharged through a discharge port by means of a gap between the grinding stones 3 and 31.