An object of the present invention is to provide a semiconductor device such as a display device, ID tag, sensor or the like at low cost by using a bottom contact type organic TFT as a switching element. In the present invention, the semiconductor layer of the bottom contact type organic TFT is formed of a polycrystalline material, and the taper width of each of the source and drain electrodes of the TFT in the direction of the channel length is smaller than the average particle size of semiconductor crystals grown on the source and drain electrodes. Alternatively, the side on the channel side of each of the source and drain electrodes of the bottom contact type organic TFT is formed so as to be convex upward with respect to the substrate surface. Alternatively, an organic compound layer different from the semiconductor layer of the bottom contact type organic TFT is made present between each of the source and drain electrodes of the bottom contact type organic TFT and said semiconductor layer, in a thickness of not more than 10 Å and not less than 1 Å.