In a thin-film field effect transistor with a MIS structure, the materials of which the semiconductor and insulating layers are made are polymers which are dissolvable in organic solvents and have a weight average molecular weight of more than 2,000 to 1,000,000. Use of polymers for both the semiconductor layer and insulating layer of TFT eliminates such treatments as patterning and etching using photoresists in the prior art circuit-forming technology, reduces the probability of TFT defects and achieves a reduction of TFT manufacture cost.