A semiconductor device includes a semiconductor substrate having a predetermined region in which a standard cell is disposed, and also includes: a first circuit connected to a first ground power line; a second circuit that is connected to a second ground power line and formed from the standard cells; and a protection circuit interposed and connected between the first circuit and the second circuit. The protection circuit includes: a resistor connected in series between the first circuit and the second circuit; and a protector that is interposed and connected between a node of the resistor on the second circuit side and the second ground power line and clamps a potential difference between the node and the second ground power line to a predetermined voltage or lower. The protection circuit is formed in a protection cell disposed in the predetermined region.