This insulated gate semiconductor device is equipped with: an insulated gate semiconductor component that turns on upon receiving a first gate voltage, which is defined in accordance with specifications, through a control terminal and outputs an input voltage, by means of switching, to a load; an output current detection means that detects an output current that is output to the load with the switching operation of the insulated gate semiconductor component; a voltage detection means that detects an on-voltage of the insulated gate semiconductor component; and a heat generation amount suppression means that sets the gate voltage to be applied to the control terminal of the insulated gate semiconductor component higher than the first gate voltage when the output current exceeds a rated output current and the on-voltage is lower than a predetermined first threshold voltage, thereby suppressing the amount of heat generated by the insulated gate semiconductor component.