A semiconductor device includes a semiconductor substrate, a gate insulating film formed over the semiconductor substrate, a gate electrode formed on the gate insulating film, a first semiconductor layer which is embedded into a portion on both sides of the gate electrode in the semiconductor substrate, and which includes Si and a 4B group element other than Si, and a second semiconductor layer which is embedded into the portion on both sides of the gate electrode in the semiconductor substrate, so as to be superposed on the first semiconductor layer, and which includes Si and a 4B group element other than Si, wherein the gate electrode is more separated from an end of the first semiconductor layer than from an end of the second semiconductor layer.