PROBLEM TO BE SOLVED: To improve fatigue resistance and tension resistance between a wire and a catch member joined to the wire.SOLUTION: A wire 16 is inserted in a joint hole 17c provided for a cylindrical member 17 to be a base material of a catch member 17 in a projecting manner, and the cylindrical member 17 is formed into first and second catch parts 17a, 17b in almost rhombic cross section in first and second V-shaped grooves 22a, 22b formed in mold dies 21a, 21b. The first and second V-shaped grooves 22a, 22b form almost rhombic obtuse angle sides, and angles K0, K1 are set K0