Exhaust gas purification system of internal combustion engine

An exhaust gas purification system of an internal combustion engine, comprising:

• an oxidation catalyst that is provided in an exhaust passage of the internal combustion engine and has an oxidizing function;
• a fuel supplying unit that supplies a fuel component to the oxidation catalyst via exhaust gas flowing into the oxidation catalyst;
• an exhaust gas purifying unit that is provided in the exhaust passage on a downstream side of the oxidation catalyst and is formed so as to include a filter which collects particulate matter in the exhaust gas, and a selective reduction-type NOx catalyst which selectively reduces NOx in the exhaust gas using ammonia as a reducing agent;
• a reducing agent supplying unit that supplies ammonia or an ammonia precursor to the exhaust gas purifying unit via exhaust gas flowing into the exhaust gas purifying unit;
• and
• an electronic control unit including a control program stored in the electronic control unit, such that upon execution of the control program by the electronic control unit, the electronic control unit is configured such that when a prescribed condition under which a part of the fuel component supplied by the fuel supplying unit passes through to the downstream side of the oxidation catalyst is satisfied, the electronic control unit controls the supply amount of ammonia or the ammonia precursor to be increased as compared to a non-passing time supply amount that is a supply amount of ammonia or the ammonia precursor to be supplied by the reducing agent supplying unit when the prescribed condition is not satisfied, and the electronic control unit is configured to control at least one of supply of the fuel component to be supplied by the fuel supplying unit and supply of the increased ammonia or ammonia precursor such that ammonia for NOx selective reduction by the increased ammonia or ammonia precursor reaches the exhaust gas purifying unit before the fuel component.