To continuously supply nails in a given posture to a groove forming machine to form a spiral groove in the axial part of a nail.

When a driving source M starts, the drive of the driving source M is transmitted to an input shaft S1 through a pulley 2, endless belt B1, pulley 1 and torque limiter T, starting the input shaft S1 to rotate. The rotation of the input shaft S1 is transmitted to the index cam of an index unit U and a pulley P3 for a timing belt. The shaft 7 connected to an output shaft S2 and the rotation side member 4 mounted on the shaft 7 are intermittently rotated receiving the rotation of the index cam. On the other hand, a supply member 17 moves toward the rotation side member 4 caused by the rotation transmitted to the pulley P3 for the timing belt, being projected in the side of the gap between respective guide rails 30, making the tip of the supply member 17 push out the axial part of a nail 10 to the position where the axial part of the nail 10 and the rotation side member 4 of a opening section 9 abut on each other.