PURPOSE: To grind a grinding wheel in keeping the extent of flatness over the full length of a cutter surface by detecting a point of time when an intermediate part of the cutter is opposed to the grinding wheel, rotating a feed screw automatically, and infeeding the grinding wheel onto the cutter successively.
CONSTITUTION: A tool rest 3 is set on a table 4, and a cutter 6 to be ground is clamped to this tool test 3, then a grinding wheel 7 is installed as capable of contact or separation to or from this cutter 6. A sliding base 5 for supporting this grinding wheel 7 is screw-engaged with a feed screw 12 which is connected to an automatic driving part 15. A point of time when an intermediate part of this cutter 6 is opposed to the grinding wheel 7 is detected by a detector 32, this feed screw 12 is rotated automatically, and the grinding wheel 7 is infeed onto the cutter 6 successively. Thus, since the grinding wheel 7 operates its infeeding when it is opposed to the intermediate part of the cutter 6, a cutter surface 6a is flattingly ground over the full length without overgrinding only an end part of this cutter surface 6a.