A semiconductor device includes a second semiconductor package, which includes a substrate and at least one semiconductor package. The substrate includes a terminal group formed on a surface thereof. At least one first semiconductor package is stacked on the substrate, and includes a plurality of flexible substrates, each of which includes a wiring group on a surface thereof and each of which is bending-deformable. At least one first semiconductor package includes a plurality of semiconductor elements mounted on a plurality of flexible substrates. Electric conduction through the second semiconductor package is established by connecting the wiring group on each of a plurality of flexible substrates to the terminal group on the substrate. Further, at least one terminal of the terminal group on the substrate is electrically connected to all of the plurality of semiconductor elements on at least one first semiconductor package, and at least one other terminal of the terminal group is electrically connected only to particular semiconductor elements of the plurality of semiconductor elements.