To solve the problem that a wire slightly obstructs a view, while the inventor has applied for a patent on a clamp metal fitting of pipe scaffolding on February 7th, 2012, a wire is attached for falling prevention since a nut is detachable even though a bolt is contrived not to project, and the wire is slid in a small hole opened at the root of the bolt.

The wire is wound around a pin at the root of the bolt for several times, the wire is put under the lower side of a cover where the pin is inserted, a hole is opened on a side face of a pipe or the like cut short so that the wire does not return, and the wire is inserted and caulked. A long wire is needed when the nut is loosened to the vicinity of a bolt distal end, however, it is preferable that it does not slacken when the nut is fastened. The wire that is wound small tries to form a large circle. To be accurate, it tries to return to be straight. This property makes both ends of the wire to be pulled at all times. Since the wire settled under the metal fitting is also pulled, there is no risk that the wire gets stuck between the pipe and the metal fitting and disconnected.