It is disclosed a semiconductor device including a silicon substrate, provided with a plurality of cell active regions in a call region, an element isolation groove, formed in a portion, between any two of the plurality of cell active region, of the silicon substrate, a capacitor dielectric film, formed in the element isolation groove, a capacitor upper electrode, formed on the capacitor dielectric film, and configuring a capacitor together with the silicon substrate and the capacitor dielectric film. The semiconductor device is characterized in that a dummy active region is provided next to the cell region in the silicon substrate.