An exhaust gas control apparatus for an internal combustion engine includes an outer tube, a downstream side catalyst held in the outer tube via a first mat, and an electric heating catalyst held in the outer tube via a second mat upstream of the downstream side catalyst. A joint of the first mat is disposed in a place other than a vertically lowermost portion.

Provided are an inorganic fiber-formed article having both high basis weight and excellent peel strength and a mat for an exhaust gas cleaning apparatus and an exhaust gas cleaning apparatus including the inorganic fiber-formed article. The inorganic fiber-formed article includes inorganic fibers and needle marks extending in the thickness direction and including vertical bundles composed of the inorganic fibers extending in the thickness direction, in which the average volume of the vertical bundles per needle mark measured by a prescribed peel test is 1.0 mm.sup.3 or more.

A method for manufacturing an exhaust gas treatment device (1), which has at least one ceramic substrate body (3, 4) for exhaust gas treatment in a tubular housing (2), includes inserting the substrate body (3) axially into the housing (2). An axial support (13), which has a supporting ring (14) and a ring-shaped support element (15) held by the supporting ring (14), is inserted axially into the housing (2) and is positioned therein such that the axial support (13) transmits a predetermined axial force (28) to the substrate body (3) via the support element (15). The axial support (13) is fixed to the housing (2) with the axially prestressed (predetermined axial force) positioning, in which the supporting ring (14) is welded to the housing (2).

An outboard motor equipped with a four-stroke engine and provided with a catalyst installation structure, in which an exhaust passage is connected to the exhaust ports of the plurality of the cylinders to lead the exhaust gas out of the engine is provided with a catalyst storage chamber configured to store a catalytic converter for cleaning up the exhaust gas, the exhaust passage being integrally formed to the cylinder block, and the catalytic converter is mounted to the catalyst storage chamber by being inserted from a lower side thereof in such a manner as that at least one side end portion thereof is fitted to the catalyst storage chamber to permit expansion of the catalytic converter in an axial direction thereof.