A semiconductor device includes a memory cell gate structure having a first gate insulating film, a first gate electrode, a second gate insulating film, and a second gate electrode, a select gate structure having a third gate insulating film and a third gate electrode including a first electrode portion, a second electrode portion, and a third electrode portion between the first electrode portion and the second electrode portion, a first impurity diffusion layer formed in a surface area of the semiconductor substrate and located at a portion which corresponds to an area between the memory cell gate structure and the first electrode portion, and a second impurity diffusion layer formed in a surface area of the semiconductor substrate and located at a portion which corresponds to an area between the first electrode portion and second electrode portion.