A semiconductor device including a package (2) having a plurality of wall portions (9a) and a plurality of conductor portions (4), a semiconductor element such as a solid-state image pickup device (1) mounted in an internal space of the base, thin metal wires (5) electrically connecting the semiconductor element and the conductor portions (4) between the wall portions (9a), a resin sealing material (7) implanted in the spaces between the wall portions (9a), and a closing member such as a cover glass (6). The region for connecting the thin metal wires (5) and the wall portion (9a) region overlap each other, so that the device can be reduced in size and in height. The cover glass (6) can not move easily from the correct position because the wall portions (9a) serve as supporting columns, thereby improving the yield.