To provide a clamp having a fastening bolt equipped with a nut lock part having a smooth surface and good handleability.

A top end of the fastening bolt 2 is formed in a cylindrical shape. A leading edge 3A of the cylindrical portion 3 at the top end of the fastening bolt 2 is crushed so that the leading edge 3A is bent inwardly in the cylindrical portion 3 and a peripheral part 3C of the cylindrical portion 3 on the proximal end side from the leading edge 3A is extended and bent outwardly. The crushed extension part 5 is utilized as the nut lock part 5 for preventing falling-off of the nut 4 screwed to a male screw portion 2A of the fastening bolt 2.