PURPOSE: To prolong the life of the high frequency coil in a high frequency matching device, to improve the productivity of a titled device and to simplify electrical connection by constituting said coil of a pipe made of stainless steel and introducing the cooling water within said pipe.

CONSTITUTION: The high frequency fed from a connector 31 at about 50Ω impedance is matched of impedance by a variable resistor 32 and a coil 33 consisting of a pipe made of stainless steel, and is conducted to a target holder 36 in the state of about ≤2.0 standing wave ratio. Then, the true potential induced in the matching coil 33 by the fluctuation in the source impedance and the change in the discharge voltage of the target is made always equal to target potential. Thus considerable fluctuations are reduced, the electrolytic corrosion of the coil 33 is reduced and the water cooling system is simplified.