To provide a nut for solve the problems, where a connecting method which passes bolts through the holes of the plural spheres cannot be trued up the edge of the bolts when the shape of the spheres are not constant, also where in the larger shape of a sphere, a bolt cannot be tightened into the nut because the bolts stops inside the sphere and can not pass through the sphere, also, in the smaller shape of a sphere, a bolt jut excessively beyond the edge of the tightened nuts, thus the excessive bolt may injure human bodies or obstruct the assembling work, when handling the sphere, and also when different kinds of spheres increase, different kinds of bolts should be increased in length to meet the shapes respectively because of the use of standard bolts.

The nut has an axle part 1 and a flange part 2 at one of the axle part 1, and a bore 3 is passed through the nut. A female screw 4 is tapped at the opposite end of the flange side, and wrenching grooves 5 are formed on the flange face.