Semiconductor device having stacked multiple substrates and method for producing same

A semiconductor device includes: a plurality of semiconductor substrates each having a pad-formed surface and being mutually laminated; a connection electrode pad formed on the pad-formed surface; a wire connecting the connection electrode pads of the plurality of semiconductor substrates so as to electrically connect the semiconductor substrates; a relay electrode pad that is provided on the pad-formed surface of a lower one of the laminated semiconductor substrates so as to be exposed by an upper one of the laminated semiconductor substrates, and that is connected to the connection electrode pad by a relay wire included in the wire; and a mounting electrode pad that is formed on a mounting surface on which the laminated semiconductor substrates are mounted, and that is connected to the relay electrode pad of the lower semiconductor substrate by the wire. In the device, the wire electrically connects the connection electrode pad of the upper semiconductor substrate to the relay electrode pad of the lower semiconductor substrate.