A semiconductor device includes an expanded semiconductor chip having a first semiconductor chip and an expanded portion extending outward from a side surface of the first semiconductor chip, a second semiconductor chip provided so as to be connected to the expanded semiconductor chip via a plurality of first bumps, and a base provided so as to be connected to the expanded semiconductor chip via a plurality of second bumps. The first bumps are provided between the first semiconductor chip and the second semiconductor chip. The second bumps are provided between the expanded portion and the base.