a first diode;

a first transistor and a second transistor, turned off when the first diode is turned off and turned on when the first diode is turned on;

a first capacitor;

a control unit, controlling whether or not to output the pulse signal to the switching element,

wherein when the switching element is in turn-on state and a collector-emitter voltage of the switching element is equal to or higher than a first predetermined voltage value, the first diode is turned on; the first transistor and the second transistor are turned on; and, after a mask time in which the first capacitor is started to be charged with a current from a current source and a voltage value at two ends of the first capacitor becomes equal to or higher than a second predetermined voltage value higher than the first predetermined voltage value, an abnormality detection signal is output to the control unit, and

the control unit stops an output of the pulse signal to the switching element in response to the abnormality detection signal,

wherein the second transistor has an emitter grounded and a base directly connected to one end of a fourth resistor and one end of a fifth resistor;

the fourth resistor has another end grounded; and

the fifth resistor has another end directly connected to an anode of the first diode.