To provide a semiconductor device including a semiconductor chip of a chip stack structure in which the back face (non-circuit face) of the semiconductor chip can have a power supply potential or the ground potential, and to provide its manufacturing method.

The back surface of the semiconductor chip A directly mounted on a wiring substrate 1 in a face-up manner is connected to an electrode pad having the power supply potential (or the ground potential) on the wiring board 1 via an anisotropy conductive film 12f. A copper foil M is adhered via an isotropic conductive film 11f to the back surface of a semiconductor chip B which is overlapped on the semiconductor chip A in a face-up manner. Since the copper foil M is opposed to a circuit face 2a of a semiconductor chip A, the semiconductor chip A and the semiconductor chip B are stacked by adhering both via an insulating film 13f. The copper foil M is connected to the electrode pad having the power supply potential (or the ground potential) on the wiring board 1, and the electrode pads of the semiconductor chip A and the semiconductor chip B are separately connected to the corresponding electrode pads on the wiring board 1.