Exhaust gas purifier for internal combustion engine

A catalytic converter of cassette type having a monolithic honeycomb structure of catalyst-coated ceramic body which is resiliently supported within an outer cylindrical metal shell. The shell includes first and second circumferential portions of an equal diameter which are at opposite axial ends thereof, and a third circumferential portion located therebetween and which has a greater outer diameter than the first and second portions. Thus bevelled areas are defined between the first and the third and between the second and the third circumferential portions. The converter is rigidly mounted in a gas passage defined by a pair of tubular members which are connected in tandem with an internal combustion engine. One of the tubular members has an inwardly extending annular rib at a given distance from the end thereof. The converter can be firmly supported at a predetermined position within said one tubular member by the engagement of one bevelled area on its outer shell with the annular rib and the abutment of the shell against the end of the other tubular member under pressure.