A semiconductor device includes a substrate including a first region and a second region, a first gate stack on the first region and including a first gate stacked insulating film and a first gate electrode on the first gate stacked insulating film, and a second gate stack on the second region and including a second gate stacked insulating film and a second gate electrode on the second gate stacked insulating film, wherein a width of the first gate stack is greater than a width of the second gate stack and the second gate stacked insulating film includes a plurality of ferroelectric material films.