An output MOS transistor has a drain connected with a power supply and a source connected with an output terminal. The short-circuit MOS transistor has a source connected with the output terminal. The short-circuit MOS transistor is formed in a semiconductor substrate connected with the power supply. A switching device is formed in a semiconductor region which is formed in the semiconductor substrate, and contains a first diffusion layer connected with the gate of the output MOS transistor and a second diffusion layer formed in the semiconductor region and connected with the drain of the short-circuit MOS transistor.