A wiring substrate has, on each of opposite faces thereof, connection pad portions to which various circuit elements are connected, and wiring traces for connecting the connection pad portions. The wiring substrate also has a through wiring portion for establishing mutual connection between the connection pad portions and the wiring traces on the front face and those on the back face. A post electrode component is formed such that it includes a plurality of post electrodes supported by a support portion. A semiconductor chip is attached to the back face of the wiring substrate, and is connected to the connection pad portions on the back face. After the post electrode component is fixed to and electrically connected to the wiring traces at predetermined positions, and resin sealing is performed, the support portion is separated so as to expose end surfaces of the post electrodes or back face wiring traces connected thereto. Another circuit element is disposed on the front face of the wiring substrate, and is connected to the connection pad portions on the front face.