PURPOSE: To improve the corrosion resistance of a bonding wire by applying pure aluminium thinly on the surface of an aluminium alloy containing a transition element as a core with a thickness of 4W20% for a cross section ratio.

CONSTITUTION: An bonding wire 3 with a diameter of 0.03mm is constructed by applying 10%, for example, for a cross section ratio a pure aluminium layer 2 on the surface of Al-1% Co alloy as a core 1. When the bonding wire of such a compound structure is applied to an IC, the resistance exists both in a general air and in resin sealing. in a general air it becomes easy to produce and maintain products with an existence of the pure aluminium, and in resin sealing it effects maintenance of a performance and reliability of a semiconductor device with an existence of an aluminium alloy containing a transition element.