PURPOSE: To prevent the disconnection and cross shorting of wiring electrodes to be laminated by forming scanning line electrodes so as to have an acute angle formed by both flanks of a first layer consisting of a low resistor and a substrate.

CONSTITUTION: The film of Al is formed as the first layer 2 of the scanning lines in common use as gate electrodes on a transparent glass substrate 1 to be formed as an array substrate. The surface of the Al of the first layer 2 is subjected to anodic oxidation by impression of a voltage to allow the oxidized film of the Al to grow as a second layer 3. The laminated layers of the first layer 2 and the second layer 3 are etched. The scanning lines in common use as the gate electrodes having such prescribed shape as to be stretched in one direction are obtd. by this stage. The tapered shape of about 30° angle formed by both flanks of the first layer 2 an the substrate 1 is formed by this etching stage. The anodic oxidation is executed again to allow the oxidized film to grow to the tapered shape of both flanks of the first layer 2. The first layer 2 is completely coated with the oxidized film of the second layer 3 including the taper shape of both flanks by this stage.