Abstract: To provide a fastening structure for fastening a left-right screw intersection forming bolt, which has a simple structure and does not loosen. A right screw nut having a recess, an elastic member having a rotation-preventing protrusion and a tongue portion, and a left screw nut having a tapered surface and a recess are included. After the bolt is tightened with the right screw nut and the elastic member is mounted, the tongue portion of the elastic member is tightened while being pressed with the left screw nut, so that the tongue portion jumps up to the recess of the left screw nut, and the left screw nut is locked and fastened. As illustrated in FIG. 9, the fastening structure can also be configured by changing the right screw nut to a left screw nut, the elastic member to an elastic member, and the left screw nut to a right screw nut.