PURPOSE: To form fine holes on an edge section precisely and simply and remarkably improve the cutting performance of a diamond grindstone by binding the edge section to a substrate then boring this edge section with a discharge drilling machine.

CONSTITUTION: An edge section 2 mixed with diamond powder and metal alloy powder and sintered is bound to the outer periphery of a disk-shaped substrate 1 made of thin steel plate. Several sheets of the substrate 1 bound with this edge section 2 are stacked and mounted on the table 4 of a discharge drilling machine (superhigh-speed fine hole boring machine). Many fine holes 3 with the diameter of 1mm or less are bored with high precision on the edge section 2 of each substrate 1 by an electrode 5 under this condition. The cutting performance and durability of a diamond grindstone can be improved by forming fine holes 3 with the diameter of 1mm or less on the edge section 2.