PURPOSE: To provide an exhaust gas purifier whose purifying functon is secure from a temporary drop as a whole even if a line discharge occurs in a manner of a short circuit at one spot and which copes favorably with a malfunction in the A.C. source.

CONSTITUTION: Exhaust gas conveyed through a gas-distributing pipe 23 is distributed among many plasma discharge treatment tubes 13 and the gas treated by these treatment tubes 13 is collected by a gas-collecting tube 25 and discharged to the outside. An A.C. source 27 is provided close to and in a manner of facing each of the plasma discharge treatment tubes 13. The A.C. source 27 is designed to produce, for example, a high voltage about 17kV for a high frequency of the order of 20 to 100kHz; the A.C. source comprises an oscillator for converting a D.C. voltage to an A.C. voltage and a leakage transformer for stepping up the output of the oscillator to a high voltage, which is supplied to the corresponding plasma discharge treatment tube 13.