PURPOSE: To prevent the disconnection of metal wirings by forming metal wirings on a thin film FET, anodically oxidizing the surface, and then forming a transparent electrode made, for example, of SnO2 or the like.

CONSTITUTION: A thin film island 12 of polysilicon is formed on a glass substrate 11, and a gate oxidized film 13 and gate electrode wirings 14 are formed. With the electrode 14 as a mask, the film 13 is etched, and source and drain 15 are formed. An interlayer insulating film 16 is covered, opened and aluminum wirings 17 are formed, anodically oxidized, and an Al2O3 film 18 is formed. Then, the film 18 on the drain is etched to form a transparent electrode 19. According to this structure, a large quantity of electrodes can be formed with citric acid solution or the like in case of the aluminum anodic oxidation with ready control. Since the Al2O2 exhibits sufficient withstand strength against etchant such as SnO2, no etching disconnection of the layer 17 occurs even if pinhole exists in case of etching the electrodes 19.