Abstract: A plasma reactor is developed on the fact that a high frequency plasma flame is larger in volume and lower in velocity and therefore a reaction material can stay therein for a relatively long period of time. The plasma reactor has a d.c. arc plasma torch provided in the upper part of the pipe which is an electrically insulative pipe high in heat-resistance and corrosion-resistance or is made up of electrically conductive components which are so designed as to prevent magnetic induction, a reaction material continuously introducing pipe opened in the vicinity of the arc plasma jet from the torch, and a high frequency coil wound around the firstly mentioned pipe coaxially with the torch.