The invention provides a semiconductor device which has a capacitor element therein to achieve size reduction of the device, the capacitor element having larger capacitance than conventional. A semiconductor integrated circuit and pad electrodes are formed on the front surface of a semiconductor substrate. A second insulation film is formed on the side and back surfaces of the semiconductor substrate, and a capacitor electrode is formed between the back surface of the semiconductor substrate and the second insulation film, contacting the back surface of the semiconductor substrate. The second insulation film is covered by wiring layers electrically connected to the pad electrodes, and the wiring layers and the capacitor electrode overlap with the second insulation film being interposed therebetween. Thus, the capacitor electrode, the second insulation film and the wiring layers form capacitors.