Irradiation with
laser light is conducted, whereby an external region of a
semiconductor thin film located on the outer side relative to a pattern of a light absorbing layer is thermally melted, and the light absorbing layer is heated, without melting an internal region of the
semiconductor thin film located on the inner side relative to the pattern. Next, the molten
semiconductor thin film is cooled, whereby microcrystal grains are produced in the vicinity of the boundary between the external region and the internal region. Further, a first lateral
crystal growth progresses from the boundary toward the outer side with the microcrystals as nuclei, whereby polycrystal grains are produced in an area of the external region. Finally, heat is transferred from the heated light absorbing layer to the semiconductor thin film, whereby the internal region is melted, and thereafter a second lateral
crystal growth progresses from the boundary toward the inner side with the polycrystal grains as nuclei, whereby further enlarged polycrystal grains are produced in the internal region.