Provided is a bonding structure of a bonding wire and a method for forming the same which can solve problems of conventional technologies in practical application of a multilayer copper wire, improve the formability and bonding characteristic of a ball portion, improve the bonding strength of wedge connection, and have a superior industrial productivity. A bonding wire mainly composed of copper, and a concentrated layer where the concentration of a conductive metal other than copper is high is formed at a ball bonded portion. The concentrated layer is formed in the vicinity of the ball bonded portion or at the interface thereof. An area where the concentration of the conductive metal is 0.05 to 20 mol % has a thickness greater than or equal to 0.1 μm, and it is preferable that the concentration of the conductive metal in the concentrated layer should be five times as much as the average concentration of the conductive metal at the ball bonded portion other than the concentrated layer.