PURPOSE: To obtain an overcurrent protective apparatus, which conducts over- current protective operation while being adapted to the area of safe operation of an actual power device, for the power device.

CONSTITUTION: A TSD 8 is installed near an IGBT 1, and reference-voltage applying means 91-95 output reference voltage VR1-VR5 to the negative inputs of comparators 51-55 on the basis of a temperature detecting signal S8. The sense terminal 3 of the IGBT is connected in common with the positive inputs of the comparators 51-55. The output signals S51 of the comparator 51 and the output signals S72-S75 of signal decision circuits 72-75 receiving output signals S52-S55 are transmitted over the input of a NOR gate 6 controlling teh ON-OFF of the IGBT. The signal decision circuits 72-75 are at an L level normally, and output decision signals at an H level when the periods of the H level of input signals continue for the allowable duration Δt2-Δt5 or more. Accordingly, overcurrent protective operation adapted to the safe operation of an actual power device is conducted.