To prevent the NOX controlling action of an NOX reduction catalyst from lowering while suppressing the supercharging efficiency of a supercharger from lowering in a exhaust emission control device of an internal combustion engine which is provided with a supercharger and capable of operating at a lean air/fuel ratio.

An engine 11 is provided with cylinders 1 to 4 containing combustion chambers. Also the branch pipe 29 of an exhaust manifold 28 is connected to the exhaust port of each of the cylinders 1 to 4. Then a three-way catalyst converter 31 is arranged in an exhaust path 13 on the downstream side of the manifold 28, and the turbine 35 of a turbocharger 33 is arranged on the downstream side of the converter 31. In the exhaust path 13, an NOX catalytic converter 47 is arranged on the downstream side of the turbine 35. In addition, the upstream side of a bypass path 43 is connected to a branch pipe 29 which is connected to a No.4 cylinder 1, and the downstream side of the path 43 is connected to the exhaust path 13 between the three-way catalyst converter 31 and turbine 35. Finally, a bypass control valve 44 is provided in the bypass path 43.