A method for making a thin-film semiconductor device includes an annealing step of irradiating an amorphous semiconductor thin film with a laser beam so as to crystallize the amorphous semiconductor thin film. In the annealing step, the semiconductor thin film is continuously irradiated with the laser beam while shifting the position of the semiconductor thin film irradiated with the laser beam at a predetermined velocity so that excess hydrogen can be removed from the region irradiated with the laser beam without evaporating and expanding hydrogen ions in the semiconductor thin film.