An improved method of forming insulated gate field effect transistors is described. In accordance with the method, gate electrodes are formed from metal such as aluminum together with wirings electrically connecting the gate electrodes. The gate electrodes are anodic oxidized by dipping them as an anode in an electrolyte to form an oxide of the metal covering them. Since the connecting wirings are covered with a suitable organic film before the anodizing, no aluminum oxide is formed thereon so that it is easy to remove the connecting wiring by usual etching.