PURPOSE: To efficiently grind a tool held by a tool holding bed with a grindstone wheel by controlling a magazine and a grindstone wheel exchanging means to move a grindstone wheel between a main shaft and the magazine with a CNC device and fitting the grindstone wheel in the magazine to the main shaft of a CNC tool grinding machine while exchanging it.

CONSTITUTION: Multiple grindstone wheels 8 of different types are stored in a magazine 3 in advance, the magazine 3 and an exchanging arm (one kind of a grindstone wheel exchanging means) 4 are controlled by a CNC device 2, a suitable grindstone wheel 8 is selected from the magazine 3 according to the machining work and fitted to the main shaft 5 of a CNC tool grinding machine. The main shaft 5 is then rotated, the main shaft 5 and a tool holding bed 19 holding a tool are moved under the control of the CNC device 2 to grind the tool. In this case, a rotation balance correcting device is provided on the grindstone wheel 8.