An object of the present invention is to increase the flexibility in the layout of an exhaust gas purification system for an internal combustion engine including selective catalytic reduction catalyst provided in an exhaust passage of the internal combustion engine and an addition device for supplying reducing agent derived from ammonia to the selective catalytic reduction catalyst, without a deterioration of the performance in reducing nitrogen oxides. To achieve the object, the exhaust gas purification system for an internal combustion engine according to the present invention is configured to supply hydrocarbon at the same time when reducing agent derived from ammonia is supplied to the selective catalytic reduction catalyst, thereby producing reducing agent that is hard to be oxidized by a precious metal catalyst.