A chip stack package may include a substrate, semiconductor chips, a molding member and a controller. The substrate may have a wiring pattern. The semiconductor chips may be stacked on a first surface of the substrate. Further, the semiconductor chips may be electrically connected to the wiring pattern. The molding member may be formed on the first substrate covering the semiconductor chips. The controller may be arranged on a second surface of the substrate. The controller may be electrically connected to the wiring pattern. The controller may have a selection function for selecting operable semiconductor chip(s) among the semiconductor chips.