PURPOSE: To make inexpensive mass production of a screw nail provided with detaining grooves by subjecting a shaft member provided with plural ridge parts in the axial direction of multiple circumferential surfaces to twisting around the axial center in such a way that the parts between the adjacent ridge parts acts as screw threads and to forming of plural detaining grooves to the respective ridge parts.

CONSTITUTION: A shaft material 11 is subjected to twisting around the axial center thereof to form the spiral shaft material 11a of which the parts between the respective ridges 12 act as screw threads 5 of a large lead angle. Detaining grooves 6 are then formed to the respective ridges 12 of the material 11a by working means such as machining, rolling, pressing or the like so that the grooves are allayed on the same circumference and are arrayed axially at predetermined intervals. The material 11a formed with the grooves 6 is subjected to a general nail manufacturing stage, by which the material 11 is cut, the head part 4 is formed and a pointed end 2 is formed. The screw nail 1 is thus continuously produced.