A device controlling a JFET power electronic switch of normally ON type, including a main gate control circuit powered by a main power source for driving the gate of the JFET switch, a protection switching device that is switchable between two states, an auxiliary circuit controlling the switching device, and an auxiliary power source whose positive terminal is connected to the source of the JFET switch and whose negative terminal is connected to the gate of the JFET switch, bypassing the gate control circuit in one of the two positions of the switching device. The switching device can be an electromagnetic or electronic switch.