A semiconductor device includes a semiconductor substrate, a first semiconductor area of a first conductive type disposed in a surface layer portion of the semiconductor substrate, a gate electrode disposed over the first semiconductor area and extending in a first direction, a dummy gate electrode disposed over the semiconductor substrate away from the gate electrode and extending in the first direction, a second semiconductor area of a second conductive type disposed, in the surface layer portion of the semiconductor substrate, between the gate electrode and the dummy gate electrode, and an interconnect connected to the second semiconductor area, wherein a concentration of carrier of a first carrier type in the semiconductor substrate under the dummy gate electrode and alongside the second semiconductor area is lower than a concentration of majority carrier in the first semiconductor area, the first carrier type being a same carrier type as the majority carrier.