To provide a semiconductor device in which the collapse of memory capacitor structure is prevented and the electrical characteristics are improved.

After a polycrystalline silicon film 10 which is to serve as a cell plate electrode 19 is formed on an inter-layer insulating film 9 covering a selection transistor, an opening part is formed in the polycrystalline silicon film 10. Then, a storage node contact hole 16 is opened which reaches a source diffusion layer 4 from the opening part, and a storage node electrode 18 is so formed that the opening part is filled with it. Since the side surface of the storage node electrode 18 is completely covered with the cell plate electrode 19 via a dielectric film 13, collapse of a capacitor is suppressed, while electrical characteristics are improved.