To provide a wire bonding method whereby a superior shearing strength is obtained, the diameters of compression-welded balls are equalized and bonding is efficient.

A ball B is formed by the spark discharge, etc., at the top end of a wire passing through a capillary 30, the capillary is moved to a heater plate 10 to press the ball B to an electrode of a semiconductor chip 20 on the heater plate 10 at a predetermined load while an ultrasonic wave is applied to the capillary to vibrate the ball. When an ultrasonic sensor 12 detects the ultrasonic vibration propagating to the heater plate 10, the ultrasonic wave application continues for a given time T from this time point and ends just when the time T has elapsed.