First laser light is irradiated (energy density of 400 to 500 mj/cm.sup.2) to a semiconductor film 102 in an atmosphere containing oxygen in order to obtain a semiconductor film 102b having large depressions and projections on the surface. Then, an oxidized film 105a formed by the irradiation of the first laser light is removed. After that, an inert gas with an oxygen density of 10 ppm or below is blown thereto, and, at the same time, second laser light is irradiated thereto (the energy density is higher than that of the irradiation of the first laser light). Thus, the surface of the semiconductor film 102b is flattened, and a semiconductor film 102c having fewer depressions and projections on the surface can be obtained.