An exhaust gas purifying catalyst, for reducing nitrogen oxides and ammonia in an exhaust gas of an internal combustion engine, in an oxidizing atmosphere, is provided. The exhaust gas purifying catalyst comprises a first catalyst having zeolite carrying platinum and copper thereon. Preferably, the exhaust gas purifying catalyst further comprises a second catalyst having zeolite carrying copper thereon. Preferably, the second catalyst is arranged upstream of the first catalyst, with respect to the exhaust gas flow.