Provided is a semiconductor device, comprising a gate electrode formed on a semiconductor substrate, source/drain diffusion layers formed on both sides of the gate electrode, a gate electrode side-wall on the side of the source/drain diffusion layer and a gate side-wall insulating film covering a part of the upper surface of the semiconductor substrate in the vicinity of the gate electrode and having an L-shaped/reversed L-shaped cross-sectional shape, and a semiconductor layer extending over the gate side-wall insulating film covering a part of the upper surface of the semiconductor substrate in the vicinity of the gate electrode.