PURPOSE: To aim at enhancing the efficiency of grinding operation, by arranging a rotable grinder shaft cylinder section and a unit for supporting a milling cutter on one and the same bed so that the shaft cylinder section is set upright, thereby a rake angle grinding may be made for relief grinding in an upset condition.

CONSTITUTION: In a grinding device for milling cutters, the rake angle of a milling cutter 15 is ground by a grinder 15 in such a condition that the shaft cylinder section 1 of the grinder is set upright. In order to carry out the relief grinding for this milling cutter 15 the latter is attached to an arbor 21 on an arm member 16 in a unit 9, and a relief grinder 4 is attached to the upper part of a shaft 2 in the upright condition of the grinder shaft cylinder section 1 so that the shaft cylinder section 1 is rotated by an angle of 90° about the shaft as a fulcrum. The grinder 4 which have been upset abuts against the cutter 15 attached to an arm 16 in the unit 9 so that the relief grinding is made by the grinder 4 which is rotated by a motor.