A technique is provided for forming a crystalline semiconductor film whose orientation is uniform by control of crystal orientation and obtaining a crystalline semiconductor film in which concentration of an impurity is reduced. A configuration of the invention is that a first semiconductor region is formed on a substrate having transparent characteristics of a visible light region, a barrier film is formed over the first semiconductor region, a heat retaining film covering a top and side surfaces of the first semiconductor region is formed over the barrier film, the first semiconductor region is crystallized by scanning a continuous wave laser beam from one edge of the first semiconductor region to the other through the substrate, then the heat retaining film and the barrier film are removed and a second semiconductor region is formed as an active layer of TFT by etching the crystallized first semiconductor region. A pattern of the second semiconductor region formed by etching is formed in a manner that a scanning direction of the laser beam and a channel length direction of the TFT are arranged in almost the same direction in order to smooth drift of carriers.