An exhaust gas-purifying catalyst of the present invention comprising a substrate, a first catalyst layer comprising a first supported catalyst, a second supported catalyst, palladium, and a first nitrogen oxide storage material, and a second catalyst layer comprising a third supported catalyst having an alloying rate of platinum and palladium of 40% or more and a second nitrogen oxide storage material, wherein a mass of the second supported catalyst is greater than a mass of the first supported catalyst and greater than a mass of the third supported catalyst.