A stack package may include a substrate having first and second faces opposite each other and an opening formed therein. The first semiconductor chip may be mounted on the first face of the substrate and include a through electrode in the middle region of the first semiconductor chip that is exposed through the opening. The second semiconductor chip may be stacked on the first semiconductor chip and electrically connected to the first semiconductor chip by the through electrode of the first semiconductor chip. The circuit pattern may be formed on the second face of the substrate and include a bonding pad arranged adjacent to the opening and electrically connected to the through electrode of the first semiconductor chip through the opening, an outer connection pad spaced apart from the bonding pad and a connection wiring extending from the opening to the outer connection pad via the bonding pad.