According to a method of manufacturing a semiconductor device of the present invention, a gate electrode is formed above a substrate, and a insulating film is formed above the gate electrode. Then, an amorphous semiconductor film is formed above the insulating film, laser annealing is performed on the amorphous semiconductor film, and the amorphous semiconductor film is changed to a crystalline semiconductor film. After that, hydrofluoric acid processing is performed on the crystalline semiconductor film, and an amorphous semiconductor film is formed above the crystalline semiconductor film where the hydrofluoric acid processing is performed so that pattern ends of the amorphous semiconductor film are arranged outside pattern ends of the crystalline semiconductor film and the amorphous semiconductor film contacts with the insulating film near the pattern ends.