PURPOSE: To make it possible to reduce initial contact pressure by turning a grinding wheel at ultralow speed to permit it to axially move, allowing the grinding wheel to be reduced in its speed or stopped due to its rotary resistance caused by making contact with a cutting blade to be ground, and stopping and positioning the axial movement of the grinding wheel.

CONSTITUTION: A grindstone frame 5 is moved to a prescribed position where a rough grindstone 10 touches a cutting blade 2 to be ground facing it, and a guidestone bench 8 is moved by a command of CPU 31 to touch the cutting blade 2 via a variable speed motor control panel 32, an axial traveling control motor 14, and a feed screw 15. Simultaneously, the rough grindstone 10 is turned at ultralow speed via a number-of-revolution control device 32 and a grindstone turning motor 9. When the rough grindstone touches the cutting blade 2 to be ground, the rotation of the grindstone turning motor 9 is disturbed and stopped due to slight contact resistance, and its stoppage is detected by a detector 12. And, this detected signal is returned to a CPU 31 via an input/output device 34 to stop the axial motor 14, allowing the positioning for initial contact to be performed. Further, a finishing grindstone 10a is also similarly positioned.