To provide a tool screwing a nut body screwed onto a bolt positively.

This tool is provided with a socket B having an engaging recessed part engaged with a receiving nut body 40, and an inserting hole inserted from its bottom on the opposite side to the open side of the engaging recessed part with part of the bottom left as a contact part with the nut body 40, and a shank A having a bolt inserting space intersecting the center line of an axial through hole 10 on one end side. The socket B is rotatably assembled onto the bolt inserting space side on the shank A on the opposite side to the open side so that the inserting hole and the through hole 10 may be disposed in series so as to insert the bolt 30 screwed into the nut body 40 received in the engaging recessed part to the inserting hole and the through hole 10, and the inserting hole and the bolt inserting space may be disposed in series so as to insert the bolt 30 screwed into the nut body 40 received in the engaging recessed part to the inserting hole and the inserting bolt space.