The invention provides a semiconductor integrated circuit preventing an electrostatic breakdown due to a surge voltage applied to a power supply wiring or a ground wiring and preventing noise interference between a digital circuit and an analog circuit. By providing a first electrostatic breakdown protection diode and a first electrostatic breakdown protection bipolar transistor in a first island region, the first electrostatic breakdown protection diode and the first electrostatic breakdown protection bipolar transistor turn on when a surge voltage is applied to a first ground wiring and protect a digital circuit against an electrostatic breakdown. Furthermore, a first isolation layer is contacted with the first ground wiring in a position that is more adjacent to a first ground pad than the digital circuit, and a second isolation layer is contacted with a second ground wiring in a position that is more adjacent to a second ground pad than an analog circuit. This prevents noise interference between the digital circuit and the analog circuit.