PURPOSE: To make a U-shaped clip and a connecting wire less separable and obtain a U-shaped clip assembly capable of being wound easily around a drum by welding together the U-shaped clip and the connecting wire in a welding length of 0.1-1.4mm.

CONSTITUTION: The wires to be clipped are fastened together with a U-shaped clip 1 by a method wherein the U-shaped clip assembly is wound around a drum with its legs 3 and 4 facing outward, the U-shaped clip assembly is fed from the drum to a clip fastening device, the wires are positioned inside the clip 1, the clip fastening device is set in operation, and the clip 1 and a connecting wire 5 are welded together in welding length (a) of 0.1-1.4mm. This makes the clip 1 and the connecting wire 5 less separable and the U-shaped clip assembly easily bendable.