In display devices using thin film transistors, a graphoepitaxy is used for a semiconductor layer crystallizing process. Thus, a display device in which crystallinity is improved, a variation in characteristics of thin film transistors is reduced, display nonuniformity is less, and a display quality is superior is provided. Steps are formed on a substrate in advance and an amorphous silicon film is formed thereon, and then laser crystallization is conducted in a direction perpendicular to the steps.