To provide a high frequency cauterization device capable of reducing reactive power, improving the efficiency of the entire device and saving energy.

A DC power source circuit part 14 for supplying DC power to a high frequency power generation part is composed of a prepower source circuit 15 on a commercial power source side and the variable power source circuit 16 of the post stage. The prepower source circuit 15 charges a capacitor 38 for smoothing through a diode 36 by pulsating current waves rectified in a diode bridge 34 when a main power switch is turned ON and charges the capacitor 38 to a higher voltage by the energy stored by an inductor 35 by the switching of a MOSFET 37 for the pulsating current waves by the input of first activation signals S1 to a gate control part 40 through a control circuit 17 by the switch operation of an operation panel 12. Also, the variable power source circuit 16 activates the gate control part 47 by second activation signals S2 by the ON operation of an output switch 4 and performs DC/DC conversion operation. Thus, the reactive power is reduced and the efficiency of this entire device is improved.