PURPOSE: To prevent the occurrence of a burr and a fracture on a workpiece by removing the burr generated on a drill through grinding and applying surface roughness of 3μmRz or less to the chip discharge direction of a drill groove and about 0.01mm radius to the external end of a cutting edge.

CONSTITUTION: A drill 8 is processed in such a way that a burr generated thereon is removed by grinding, the surface roughness thereof is 3μmRz or less at a groove 9 in a chip discharge direction and an edge 11a of about 0.01mm radius is formed on the external end 11 of a cutting edge part 10. And the cutter part of the drill 8 is immersed, for example, in an ionizing solution and a negative electrode is provided in the solution, thereby applying electrolytic polishing to the drill 8 under an electric charge.