A semiconductor device includes a gate insulation film provided on a semiconductor substrate, a gate electrode provided on the gate insulation film, a pair of first diffusion layers, a pair of second diffusion layers which are provided in the semiconductor substrate in such a manner that the gate electrode is interposed between the second diffusion layers, the second diffusion layers have a lower impurity concentration than the first diffusion layers, contact wiring lines provided on the first diffusion layers, respectively, and a first insulation layer which is an insulation layer formed in at least one of the second diffusion layers between the gate electrode and the contact wiring lines, the first insulation layer having a greater depth in the semiconductor substrate than the first diffusion layer and a less depth than the second diffusion layer.