To provide a joint of a gold ball and a copper pad, the joint being made stable with less influence of a surface state of the copper pad.

A shielding thin film 4 comprised of either member of Ti, TiN, TaN is formed on the copper pad 3 formed of an uppermost layer copper wiring 2. At the time of wire bonding of the copper pad 3 and the gold ball 6 that form the shielding thin film 4, the copper pad 3 and the gold ball 6 are joined with each other by exposing a new surface of copper of the copper pad 3 by breaking the shielding thin film 4 formed on the copper pad 3 by load from the gold ball 6 and by ultrasonic vibration. It is possible to obtain the stable joint of the copper pad 3 and the gold ball 6, in which mutual diffusion of copper and gold sufficiently proceeds without being influenced by a surface state of copper oxide etc. produced owing to oxidation of the surface of the copper pad 3.