PURPOSE: To heat the purifying means in an extremely short time utilizing microwave energy, to clean the harmful matter at the cold start of a gasoline engine and to purify the exhaust gas from the engine with high reliability by using this purifier.

CONSTITUTION: This purifier is provided with a purifying means 9 obtained by depositing a wave absorber 18 and a catalyst 19, as required, on a cermic carrier, a purifying means, a means for heating the purifying means using microwave energy and a ternary catalyst. The harmful matter contained in the exhaust gas is efficiently cleaned by this constitution.