PURPOSE: To cut and form grooves onto a semiconductor substrate free of edge chipping by forming the top edge of a grindstone into convex form and allowing plural kinds of abrasive material having different particle size to be attached onto the single grindstone.

CONSTITUTION: The top edge of a grindstone 11 is formed into convex form, and the abrasive material 14 having rough particle size is attached onto the thin part A, and the abrasive material having fine particle size is attached onto the thick part B, and a semiconductor substrate 12 is efficiently cut by the rough abrasive material 14 on the thin part A. The edge chipping 13 generated at this time is cut by the thin abrasive material 15 on the thick part B, and the section of the cut groove is formed into smooth state.