PURPOSE: To obtain a wire bonding device capable of performing swiftly the setting of discharge conditions at the time of formation of a ball by a method wherein the device is provided with respective specified means, a ball diameter measuring means, a storage means, a comparison means and a discharge condition setting means.

CONSTITUTION: Discharge is generated between a torch electrode 10 and a wire 7 made to project from the point of a capillary 8 and a ball 7a is formed on the point of the wire 7. Such a wire bonding device 1 is provided with a ball diameter measuring means 12 for measuring the diameter of the ball 7a formed by the discharge, a storage means 16 for storing a desired prescribed ball diameter and a comparison means 17 for comparing a measured ball diameter with a stored prescribed ball diameter. Moreover, the device 1 is provided with a discharge condition setting means 11 for correcting at least one of a current which is applied at the time of discharge, a discharging time and the projection length of the wire 7 from the point of the capillary 8, which are attributed to the main cause of the size of a ball diameter to be formed in a direction, to which a ball diameter measured at the time of next discharge on the basis of the compared result approaches the prescribed ball diameter.