An interconnecting substrate for carrying a semiconductor device, comprising: an insulating layer; an interconnection set on an obverse surface of the insulating layer; an electrode which is set on a reverse surface side of the insulating layer and formed in such a way that, at least, a lateral face of an obverse end of the electrode is all round brought into contact with the insulating layer, while, at least, a reverse surface of the electrode is not in contact with said insulating layer; a via conductor which is disposed on an obverse surface of the electrode and formed in the insulating layer so as to connect this electrode with the interconnection; and a supporting structure on the surface of the insulating layer.