Disclosed is a high-voltage pulse generating circuit comprising an inductor, a first semiconductor switch and a second semiconductor switch connected in series between both ends of a DC power supply unit. A diode unit is connected between a gate terminal of the first semiconductor switch and one end of the inductor (namely, one end of a primary coil). A resistor is connected between the gate terminal of the first semiconductor switch and the one end of the inductor. The resistor serves as a gate current-supplying means which allows a gate current to flow to the first semiconductor switch when the second semiconductor switch is turned on.