A semiconductor device in which TFTs of suitable structures are arranged depending upon the performances of the circuits, and storage capacitors are formed occupying small areas, the semiconductor device featuring high performance and bright image. The thickness of the gate-insulating film is differed depending upon a circuit that gives importance to the operation speed and a circuit that gives importance to the gate-insulating breakdown voltage, and the position for forming the LDD region is differed depending upon the TFT that gives importance to the countermeasure against the hot carriers and the TFT that gives importance to the countermeasure against the off current. This makes it possible to realize a semiconductor device of high performance. Further, the storage capacity is formed by a light-shielding film and an oxide thereof to minimize its area, and a semiconductor device capable of displaying a bright picture is realized.