PURPOSE: To reduce the falling-off of chippings and crystalline particles on a cut-off trench side by a method wherein a work is to be cut off using three layer structured blade in different abrasive grain sizes for lowering the cutting resistance and improving the cutting efficiency.

CONSTITUTION: The outer parts 2 of a blade section comprising Cu-Sn base, etc., contain the diamond grinding stone particles exceeding # 2000. At this time, the central part 1 is to be three layer structured containing the diamond grinding stone particles not exceeding #1500. A work to be cut off (single NiO oxide or compound oxide of NiO and CoO, etc.) is cut off using such a three layer structured blade. By the application of this three layer structured blade, the chippings produced during the cutting off step can be made smaller for cutting down the operating time due to the eliminated chip removing step during the layer polishing step. Furthermore, the cutting efficiency can be improved by the lowered cutting resistance for avoiding the breakdown, scattering of the cut off chippings thereby increasing the yield.