The invention is directed to providing a package type semiconductor device with high reliability and smaller size and a method of manufacturing the same. A semiconductor substrate formed with a device element and a pad electrode on its front surface is prepared. The semiconductor substrate is then selectively etched from its back surface to form an opening. A second insulation film is then formed covering the side and back surfaces of the semiconductor substrate. First and second insulation films on the bottom of the opening are then selectively removed to expose a portion of the pad electrode. A wiring layer is then formed along the side surface of the semiconductor substrate, being electrically connected with the exposed pad electrode. An electrode connect layer is then formed covering the wiring layer. A protection layer is then formed covering the back surface of the semiconductor substrate and having an opening in a region for formation of a sidewall electrode. Then, the sidewall electrode is formed in a region exposed by the opening of the protection layer.