In a thin-film field-effect transistor having metal/insulator/semiconductor (MIS) structure, the semiconductor layer is formed of an organic compound, and the insulator layer is formed of an organic compound which is soluble in an organic solvent and exhibits spontaneous polarization similar to ferroelectric material. The transistor exhibits n-type transistor characteristics when polling is conducted by applying a voltage which is not less than a coercive electric field and not more than a withstand voltage between source and gate electrodes, and absent polling, the transistor exhibits p-type transistor characteristics.