Exhaust gas purification system for internal combustion engine

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

• a selective catalytic reduction catalyst which is provided in an exhaust passage of the internal combustion engine and which includes a precious metal catalyst;
• an addition device which is provided in the exhaust passage upstream of the selective catalytic reduction catalyst and which adds reducing agent derived from ammonia to exhaust gas;
• a fuel supply device which supplies fuel to exhaust gas at a location upstream of the selective catalytic reduction catalyst;
• a control unit which causes the fuel supply device to supply fuel at the time when reducing agent is added to exhaust gas by the addition device;
• and
• a measuring unit which measures a temperature correlating with the temperature of the selective catalytic reduction catalyst;
• wherein the control unit changes the amount of reducing agent added by the addition device and the amount of fuel supplied by the fuel supply device in accordance with the temperature measured by the measuring unit.