To provide a catalyst for clarification of exhaust gas for efficiently clarifying HC, CO and NOx and with low oxidation activity of SO2.

A catalyst consisting of a porous oxide carrier incorporated with at least a basic oxide selected from alkali metals, alkaline earth metals and rare earth elements and a catalytic precious metal carried on the carrier is treated with an acid. It is estimated that the carrier or the catalytic precious metal is changed in properties with the acid treatment and the oxidation activity for SO2 is decreased without decreasing the oxidation activity for HC and CO.