A method of manufacturing a semiconductor device is disclosed in which a metallic deposit is stably formed on the anode side with small variation in film thickness, and plating is prevented on the cathode side without carrying out any additional processing on the cathode side. The processed anode side causes no interference in subsequent processing. Insulator films are used to cover a scribe line, as well as a field plate or an open electrode provided on a surface of a silicon substrate before Ni electroless plating of an aluminum electrode is performed to form a metallic deposit on the electrode.