When annealing of a semiconductor film is conducted using a plurality of lasers, each of the distances between laser irradiation regions is different. When a lithography step is conducted in accordance with a marker which is formed over a substrate in advance after the step, light-exposure is not correctly conducted to a portion crystallized by laser. By using a laser irradiation region obtained on a laser irradiation step as a marker, light-exposure is conducted by making a light-exposure position of a stepper coincide with a large grain size region in the laser irradiation region. A large grain size region and a poorly crystalline region are detected by utilizing a thing that scattering intensity of light is different between the large grain size region and the poorly crystalline region, thereby determining a light-exposure position.