The bonding time of a metallic ribbon is shortened in the semiconductor device which connects a lead frame with the bonding pad of a semiconductor chip with a metallic ribbon. The bottom of the wedge tool is divided into two by the V-groove at the first branch and the second branch. In order to do bonding of the Al ribbon to the source pad of the silicon chip, and the source post of the lead frame, first, the first branch and second branch of the wedge tool are contacted by pressure to Al ribbon on the source pad, and supersonic vibration is applied to it. Subsequently, the first branch is contacted by pressure to Al ribbon on the source post, and supersonic vibration is applied to it. Here, since the width of the first branch is narrower than the width of the source post, Al ribbon is not joined at the end surface of the width direction of the source post.