PURPOSE: To make it possible to improve the bonding strength between a wire and an electrode and to miniaturize a bonding pitch by forming the surface of the electrode in a protruding shape, compressing the wire to the protruding surface of the electrode, generating ultrasonic wave vibration, and bonding the wire to the electrode.

CONSTITUTION: The end part of a connecting wire 13 comprising, e.g. aluminum raw material, is mounted on a surface 11a of an electrode 11 which is provided on a substrate 12 of a semiconductor device. The wire 13 is compressed to the surface 11a of the electrode 11 with a wedge 14 of an ultrasonic wave bonding apparatus. The surface 11a of the electrode 11 is formed in a protruding state toward the wire 13. The protruding surface 11a can be readily formed by forming the protruding part, e.g. on the electrode 11 which is provided on the substrate 12 and covering the facing surface to the wire 13 with a metallic thin film such as aluminum and gold. The wedge 14 for compressing the wire 13 to the protruding surface 11a of the electrode 11 is driven by the driving part of the ultrasonic wave bonding apparatus. The wire 13 is vibrated with the ultrasonic waves. The wire 13 is plastically deformed along the surface 11a of the electrode 11. The wire 13 is flattened in a concave shape and bonded to the electrode 11.