EXHAUST GAS PURIFICATION APPARATUS FOR AN INTERNAL COMBUSTION ENGINE

An amount of NOx discharged from an internal combustion engine at the time of reducing the NOx stored in an NOx storage reduction catalyst is decreased. In an exhaust gas purification apparatus for an internal combustion engine which includes an NOx storage reduction catalyst arranged in an exhaust passage of the internal combustion engine for storing NOx in exhaust gas and reducing the NOx when an air fuel ratio of the exhaust gas is equal to or less than a stoichiometric air fuel ratio, an air fuel ratio control unit to change the air fuel ratio of the exhaust gas in the internal combustion engine, and an EGR device connecting between the exhaust passage and an intake passage of the internal combustion engine for supplying a part of the exhaust gas to the intake passage as an EGR gas, provision is made for an EGR ratio control unit that controls the EGR device in such a manner that in cases where the NOx stored in the NOx storage reduction catalyst is reduced by changing the air fuel ratio in the internal combustion engine, an EGR ratio becomes higher when the target air fuel ratio is low than when the target air fuel ratio is high.