An end part of a first electric wire bundle (81) comprising 3 copper wires is twisted and a plurality of troughs (73) is formed along a length direction of the first electric wire bundle (81). A portion of second electric wires (82), which are 3 aluminum wires, is fit into at least one of the plurality of troughs (73) formed on the twisted portion of the first electric wire bundle (81) along the length direction thereof and at the same time, an end part of the second electric wires (82) is wound around the twisted portion of the first electric wire bundle (81) in a spiral. The twisted portionof the first electric wire bundle (81) and the portion of the second electric wires (82) wound in a spiral are bonded by a bonding material (75). The portions of the first electric wire bundle (81) and the second electric wires (82) bonded via the bonding material (75) are covered by an insulating material (71).