The semiconductor device includes a first transistor including a first impurity layer of a first conductivity type formed in a first region of a semiconductor substrate, a first epitaxial semiconductor layer formed above the first impurity layer, a first gate insulating film formed above the first epitaxial semiconductor layer, and a first gate electrode formed above the first gate insulating film, and a second transistor including a second impurity layer of the second conductivity type formed in a second region of the semiconductor substrate, a second epitaxial semiconductor layer formed above the second impurity layer and having a thickness different from that of the first epitaxial semiconductor layer, a second gate insulating film formed above the second epitaxial semiconductor layer and having a film thickness equal to that of the first gate insulating film and a second gate electrode formed above the second gate insulating film.