PURPOSE: To prevent clogging of a capillary tool with a metal wire in the case of forming a ball part by applying an ultrasonic vibration to the tool simultaneously when a spark discharge is generated between the wire and a spark torch.

CONSTITUTION: When a spark discharge is generated between a metal wire 5 and a spark torch 7, an ultrasonic vibration is simultaneously applied to a capillary tool 4. That is, the tool 4 is moved down toward a semiconductor chip 1 thereby to press.connect a ball part 5a at an end of the wire 5 to the chip 1. In this case, the vibration is applied to the tool 4 by ultrasonic wave oscillating means mounted at a tool horn 6 to increase a connecting strength of the part 5a to the chip 1. Thus, adherence of cinder of a film generated from the wire 5 due to the spark discharge to the tool 4 is prevented, and clogging of the tool is prevented.