An NOx reduction catalyst and an exhaust system using the same may include an NOx reduction catalyst mounted at an exhaust pipe through which exhaust gas passes, wherein the NOx reduction catalyst includes first and second catalyst layers coated on a carrier, the first catalyst layer being disposed close to the exhaust gas, and the second catalyst layer being disposed close to the carrier, wherein a portion of nitrogen oxide contained in the exhaust gas is oxidized while passing through the first catalyst layer, and the oxidized nitrogen oxide is stored in the second catalyst layer, wherein the nitrogen oxide stored in the second catalyst layer is released through a substitution reaction with an additionally injected fuel, and wherein the released nitrogen oxide is reduced by the additionally injected fuel in the first catalyst layer.