A catalytic element is added to an amorphous semiconductor film and heat treatment is conducted therefor to produce a crystalline semiconductor film with good quality, a TFT (semiconductor device) with a satisfactory characteristic is realized using the crystalline semiconductor film. A semiconductor layer includes a region containing an impurity element which has a concentration of 1×1019/cm3 to 1×1021/cm3 and belongs to group 15 of the periodic table and an impurity element which has a concentration of 1.5×1019/cm3 to 3×1021/cm3 and belongs to group 13 of the periodic table, and the region is a region to which a catalytic element left in the semiconductor film (particularly, the channel forming region) moves.