Abstract: To enable the positioning of an axle nut with a clamp. A split clamp axle holder is provided on each of the lower portions of left and right front forks of a motorcycle. The ends of an axle of the motorcycle are respectively fastened to the axle holders. The axle holder which supports a threaded small diameter portion of the axle has a peripheral groove extending in a radial direction from an axle opening. An axle nut is locked inside the axle opening by tightening clamp parts positioned on both ends of a slot formed in the axle holder with a bolt. One end of the axle nut includes a collar part and the other end includes a peripheral groove. A central part of the axle nut includes a cylindrical part which is inserted into the axle opening with the side having the peripheral groove entering first. By engaging a circlip in the peripheral groove protruding from the other end of the axle nut, it is possible to properly locate the axle nut on the axle holder.