To solve the problem wherein the mainstream of a PM removal process of diesel exhaust gas at present is the filter system, this system maintains the PM removal effect by simultaneous use of an oxidation catalyst composed of platinum and a rare earth element, but unable to completely avoid the occurrence of fatal clogging possessed by the filter system, and a breakaway from a filter system is demanded from an international resource state of increasing more and more in cost increase and the difficulty of acquisition of rare metal.

The exhaust gas flowing in a ceramic reaction pipe passing through the axis of one or a plurality of hybrid mode type resonators of an atmospheric pressure microwave plasma generator, is turned into plasma in the respective resonators, and PM in the exhaust gas is burnt and removed. Combustion is promoted by preventing an ignition delay in the PM by arranging a combustion chamber for installing an object for removing an exhaust flow speed and generating a turbulent flow, by expanding a reaction pipe diameter in the tip vicinity of the plasma. When performing this system in a multistage shape when necessary, a combustion removal of the exhaust PM can be reliably performed.