It is an object of the present invention to surely protect a predetermined semiconductor element or a predetermined semiconductor element group in an analog block from a noise generated from a digital block. A semiconductor device according to the present invention includes a semiconductor substrate, a digital block to be a region in which a digital circuit is formed and an analog block to be a region in which an analog circuit is formed, arranged by separating an upper surface of the semiconductor substrate and a substrate potential fixing region provided on the semiconductor substrate so as to surround in a planar view the predetermined semiconductor element group in the analog block, and a pad connected to the substrate potential fixing region and receiving a predetermined potential from an external part.