Disclosed is a method for crystallizing a single crystalline Si film on an amorphous substrate, such as a glass substrate or a plastic substrate. The method includes the steps of selectively irradiating the laser beam onto a pixel section TFT forming region and a peripheral circuit TFT forming region of the amorphous silicon film through primary and secondary laser irradiation processes, thereby forming a poly-silicon film and irradiating the laser beam onto one of grains formed in the poly-silicon film through a third laser irradiation process, thereby forming a single crystalline silicon region having a desired size on a predetermined portion of the amorphous silicon film. The amorphous silicon film is locally crystallized into the single crystalline silicon film so that characteristics of TFTs for the pixel section and the peripheral circuit are improved while ensuring high uniformity.