A catalyst for treating exhaust gases containing nitrogen monoxide, carbon monoxide and volatile organic compounds includes a plurality of layers, an upper layer of which has an active component contained uniformly therein and a lower layer of which has no active component contained therein. The catalyst is obtained through the steps of: forming the lower layer by coating the surface of substrate with a slurry of a porous inorganic compound, followed by drying; and forming the upper layer, which is to be the top surface of the catalyst, by coating the surface of the lower layer with a slurry of a porous inorganic compound that has the active component composed of one or more precious metals supported thereon, followed by drying. The oxidation power of the resulting catalyst is enhanced without increasing the amount of precious metal supported thereon.