A semiconductor device comprises a semiconductor substrate including a diffusion area, a capacitor provided above the semiconductor substrate and including a lower electrode, a dielectric film, and an upper electrode, a plug provided between the semiconductor substrate and the capacitor and having a lower end connected to the diffusion area and an upper end connected to the lower electrode, and a dummy plug provided between the semiconductor substrate and the capacitor and having a lower end not connected to the diffusion area and an upper end connected to the lower electrode.