To provide: a technique capable of suppressing a titanium nitride film that is exposed at the side surface of an opening from turning into a titanium oxide film even when water permeates the opening over a pad from outside a semiconductor device and thus improving the reliability of the semiconductor device; and a technique capable of suppressing a crack from occurring in a surface protective film of a pad and improving the reliability of a semiconductor device. An opening is formed so that the diameter of the opening is smaller than the diameter of another opening and the opening is included in the other opening. Due to this, it is possible to cover the side surface of an antireflection film that is exposed at the side surface of the other opening with a surface protective film in which the opening is formed. As a result of this, it is possible to form a pad without exposing the side surface of the antireflection film.