A lead frame including a stage and a plurality of terminals is embedded in a mold resin including a base portion for mounting a semiconductor chip (e.g. a microphone chip), a peripheral wall disposed in the periphery of the base portion, and an extension portion extended outside of the peripheral wall, thus forming a package base. A plurality of holes is formed in the peripheral wall so as to expose the internal connection surface of the stage and the internal connection surfaces of the terminals. An extension portion of the stage is exposed on the extension portion of the mold resin in which the surfaces of the terminals are embedded. An extension portion (e.g. a brim) of a cover composed of a conductive material is attached to the extension portion of the mold resin of the package base, thus completely producing a semiconductor device.