Pressure sensor

A pressure sensor includes a semiconductor substrate having a diaphragm in which an electrical circuit including a gauge resistance is formed, an insulation film provided on a surface of the semiconductor substrate, an Al film provided on the insulation film and electrically connected to the electrical circuit through a conductor hole of the insulation film, an Au film provided on the Al film through a Ti film, a first protective film which covers the Al film and has an opening portion from which a portion of the Au film is exposed. In the pressure sensor, a second protective film made of polyimideamide or polyimide covers at least the surface of the Au film exposed from the first protective film, and a vicinity of the opening portion of the first protective film. Therefore, corrosion resistance of the Al film can be prevented while the pressure sensor has a reduced component number.