In the case of providing an LDD region for a TFT, it is necessary to form separately an insulating film to be a mask or to contrive the shape of a gate electrode layer in order to have the concentration difference in impurities injected in a semiconductor film; therefore, the number of patterning steps has increased as a matter of course and the step has become complicated. A semiconductor device according to one feature of the invention comprises a semiconductor layer including a channel region, a pair of impurity regions, and a pair of low-concentration impurity regions; and a gate electrode layer having a single layer structure or a laminated structure, of which film thickness is not even, which is formed to be in contact with the semiconductor layer by sandwiching a gate insulating film therebetween. Particularly, the gate electrode layer, of which film thickness is not even, can be formed easily by employing a droplet discharging method; thus, the convenience of the droplet discharging method can be taken with full advantage.