100 v to a dc voltage of 300 to 1000 v the high voltage switching circuit 6 is connected at bases of four transistors 6a 6b 6c and 6d to an oscillator 9 the oscillator 9 is connected to a control unit 100 for controlling the same oscillator 9 generates a pulse ranging in frequency from 3 mhz to several mhz to be supplied directly to the transistors 6a and 6d and through an inverter 10 to the transistors 6b and 6c fig2 a shows a situation where the syringe needle disposer shown in fig1 is received into a casing 11 in the bottom of the casing 11 are provided a cooling water channel 12 and a power source conduit 13 and a drawer 14 for drawing off the treated syringe needles is provided therebetween the cooling water channel 12 is connected to a nozzle 16 through a hose 15 and the drawer 14 is designed in such a way that it can be drawn off in the direction perpendicular to the plane of the paper the power source conduit 13 has the high voltage switching circuit 6 the transformation rectification circuit 7 the oscillator 9 controlled by controlled unit 100 and the inverter 10 shown in fig1 and it is activated with a switch 17 fig2 b shows a sectional view taken along a line b b in fig2 a the drawer 14 is positioned downwards.