To solve the problem, wherein a fuse is required for a circuit where main current flows for detecting a fault of a semiconductor device, that the circuit is enlarged in a large capacity device and that it takes much time for restoring the fault for exchange of the fuse, in a system for installing the fuse in a driving circuit and for positively melting the fuse so as to protect the driving circuit, when the semiconductor device breaks down.

In the semiconductor driver, a first thermistor is arranged in an ON-gate resistor, and a second thermistor in an OFF-gate resistor; the driver is constituted in such a way that current regularly flows to the respective thermistors; and a switch element of driving circuit output is turned off by using a change of a thermistor resistance value, when a temperature of one gate resistor rises.

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