PURPOSE: To achieve saving of process and improvement of performance by folding a foil once or more and superposing the same, installing the superposed foil part on the electrode side and directly resistance-weld the foil and wire.

CONSTITUTION: A foil 2 is bent at a suitable length and the bent foil part 2a is superposed. With this folded foil part 2a being faced to the upper electrode 7, a wire 1 is installed to the lower electrode 8. The foil 2 and wire 1 is resistance-welded while being contacted at the portions inner than the mutual boundary of the foil 2 and wire 1 by a tapered electrode 7 having the end of a width smaller than the folded length of the folded foil part 2a or an electrode of truncated conical shape to obtain a bonded region 6b, and this results in considerably improved bonding strength. If, in this case, a groove 8a matched to the shape of the wire 1 is formed at the end face of the lower electrode 8 and welding is done by installing the wire 1 in this groove 8a, then the range of weldable current increases and the higher bonding strength may be obtained.