To provide a thin film transistor having a high field effect mobility and a small variation in characteristics thereof, a second amorphous semiconductor layer patterned in a predetermined shape is formed on a first crystalline semiconductor layer 17 for constituting source and drain regions. By irradiating an irradiated region 21 of continuous wave laser beam while scanning along a channel length direction, the second amorphous semiconductor layer is crystallized to form a second crystalline semiconductor layer 22. The first crystalline semiconductor layer 17 is crystallized by selectively adding nickel and therefore, an orientation rate of {111} is increased. By irradiating laser beam, crystals of the second amorphous semiconductor layer grow by constituting a seed by the first crystalline semiconductor layer 17 oriented to {111} and therefore, a region 22a for constituting a channel forming region is also oriented highly to {111} and a direction of a crystal grain boundary becomes parallel with the channel length direction.