In a memory cell array region and a source contact region defined in a surface of a semiconductor substrate, a memory cell transistor including a floating gate electrode and a control gate electrode is formed. In a gate contact region, a dummy floating gate electrode is arranged to partially be superimposed on a dummy element formation region in a two-dimensional view. In a first interlayer insulating film and a second interlayer insulating film covering the memory cell transistor, a contact plug is formed to penetrate the first interlayer insulating film and a via is formed to penetrate a second interlayer insulating film.