Abstract: A protection circuit structure for an internal semiconductor integrated circuit. The protection circuit structure includes a first protection circuit having at least a first input pin and a first discharge pin, a second protection circuit having at least a second input pin and a second discharge pin and a switching device connecting between the first and second protection circuits. The switching device is biased by a potential difference between the first and second discharge pins. The switching device permits operating one of the first and second protection circuits to accomplish a discharge in replacement of an inoperative first or second discharge pin. The switching device takes the ON state when biased by a predetermined voltage or higher which interrupts the internal semiconductor integrated circuit. The switching device connects between wiring lines which respectively connect to the first and second discharge pins.