PURPOSE: To provide a jig for nailing which can nail correctly a nail having a flange and a rod penetrating movable through the flange, even in a narrow place.

CONSTITUTION: This jig for nailing is provided with a main body 11 having an almost cylindrical form whose inner wall forms a guide hole 15, and a pin member 21 fitted slidable to the guide hole 15. The main body 11 has a thick wall part 11a where the diameter size of the guide hole 15a is set almost equal to the diameter size of the rod 3 of a nail 1, and a thin wall part 11b where the diameter size of the guide hole 15b is set larger than the diameter size of the rod 3 of the nail 1. The pin member 21 is fitted closely to the guide hole 15a, and it has a small diameter part 21a where the size in the axial direction is set almost equal to the size of the thick wall part 11a in the axial direction, and a large diameter part 21b fitted closely to the guide hole 15b, whose size in the axial direction is set larger than the size of the thin wall part 11b in the axial direction.