PURPOSE: To reduce the generation of a defective product and to obtain a stabilized product of good accuracy by expanding the hole having smaller diameter than the necessary bore in the necessary bore by the working means of a drill, etc., after piercing it by pulse laser machining.

CONSTITUTION: The hole in smaller diameter than a finally desired bore is pierced the pulse laser machining of one pulse only. This small bore hole is then expanded in the necessary bore by the work means of a drill, etc. Or the diameter of a needle stock is reduced by grinding, etc., after piercing the necessary product by laser machining of one pulse only on the needle stock having larger diameter than a finally desired needle diameter. Or said two methods are executed jointly. The stabilized product of good accuracy is thus subjected to mass production at low cost.