A semiconductor device having a transistor gate length greatly reduced as a result of promotion of semiconductor integrated circuit miniaturization where leakage current generation in a gate insulating film can be inhibited to enhance the transistor function. The semiconductor device includes: a semiconductor substrate having a main surface; a pair of source/drain regions formed over the main surface of the semiconductor substrate; a gate insulating film formed, over a region between the pair of source/drain regions, to be in contact with the main surface; and a gate electrode formed to be in contact with the upper surface of the gate insulating film. In the semiconductor device, the gate electrode has a length of less than 45 nm in a direction from a first one of the pair of source/drain regions to a second one of the pair of source/drain regions, and the gate insulating film has an antiferroelectric film.