An exhaust gas purification system for an internal combustion engine, comprising: a low pressure EGR mechanism that is equipped with a low pressure EGR passage which serves to introduce a part of an exhaust gas flowing through a portion of the exhaust passage downstream of a turbine of a centrifugal supercharger to a portion of an intake passage upstream of a compressor as a low pressure EGR gas, and a low pressure EGR valve which serves to change a channel cross section of said low pressure EGR passage; a selective reduction type catalyst that is arranged in a portion exhaust passage of the internal combustion engine at the upstream side of a connection portion of said low pressure EGR passage; a supply device which serves to supply an ammonia derived compound to said selective reduction type catalyst, and is arranged in such a manner that the ammonia derived compound is able to be supplied into the exhaust passage at a location upstream of a connection portion of said low pressure EGR passage; and control means for causing said supply device to supply the ammonia derived compound therefrom when said low pressure EGR valve is in a valve open state, characterized in that said control means calculates, by using a bed temperature of the selective reduction type catalyst as a parameter, an amount of saturation of ammonia which is an amount of ammonia that can be adsorbed by said selective reduction type catalyst, and controls said supply device in such a manner that an amount of ammonia derived compound more than the amount of saturation of ammonia is supplied to said selective reduction type catalyst when said low pressure EGR valve is in a valve open state. a low pressure EGR mechanism that is equipped with a low pressure EGR passage which serves to introduce a part of an exhaust gas flowing through a portion of the exhaust passage downstream of a turbine of a centrifugal supercharger to a portion of an intake passage upstream of a compressor as a low pressure EGR gas, and a low pressure EGR valve which serves to change a channel cross section of said low pressure EGR passage; a selective reduction type catalyst that is arranged in a portion exhaust passage of the internal combustion engine at the upstream side of a connection portion of said low pressure EGR passage; a supply device which serves to supply an ammonia derived compound to said selective reduction type catalyst, and is arranged in such a manner that the ammonia derived compound is able to be supplied into the exhaust passage at a location upstream of a connection portion of said low pressure EGR passage; and control means for causing said supply device to supply the ammonia derived compound therefrom when said low pressure EGR valve is in a valve open state, characterized in that said control means calculates, by using a bed temperature of the selective reduction type catalyst as a parameter, an amount of saturation of ammonia which is an amount of ammonia that can be adsorbed by said selective reduction type catalyst, and controls said supply device in such a manner that an amount of ammonia derived compound more than the amount of saturation of ammonia is supplied to said selective reduction type catalyst when said low pressure EGR valve is in a valve open state.