A semiconductor element sealed substrate including a semiconductor element covered by an insulating layer is fabricated while a wiring substrate formed by stacking wiring layers is fabricated by a process different from the process of fabricating the semiconductor element sealed substrate. Next, the semiconductor element sealed substrate and the wiring substrate are stacked on each other in such a way that electrode terminals of the semiconductor element and corresponding conductive bumps on the outermost wiring layer face each other. The electrode terminals and the conductive bumps are thus connected to each other.