PURPOSE: To efficiently manufacture a U-bolt having a seat plate, and correctly mount the seat plate by press-fitting the seat plate to the position of a stepped part through a tapered part.

CONSTITUTION: A rod is cut to the prescribed length, and both ends are cut to a slightly small diameter to the prescribed position of a seat plate 2, and a stepped part (a) is cut to have an angle of approximately 3°. The off-centered seat plate 2 which is blanked by a blanking machine is fitted into the small diameter part so that the inner diameter of the seat plate may be smaller, and the seat plate is simultaneously press-fitted from the right and left by a press-fitting machine through a tapered part to the prescribed position of the stepped part (a). The stepped part (a) is cut to the angle of approximately 3°, and the corner part is raised by the press-fitting, and strongly reinforced against the screw tightening torque. In addition, the threading is executed on the small diameter part on both end sides of the rod 1 to the stepped part (a) by a thread rolling machine, and the rod 1 is bent in a U-shape from the center in a symmetrical manner in the right- to- left direction.