An exhaust purification system of an internal combustion engine comprising: an exhaust treatment catalyst arranged in an engine exhaust passage, an electronic control unit, and a heat and hydrogen generation device able to feed only heat or feed heat and hydrogen to the exhaust treatment catalyst to warm up the exhaust treatment catalyst, said heat and hydrogen generation device being provided with a reformer catalyst into which combustion gas of fuel and air is fed, heat and hydrogen being generated in said heat and hydrogen generation device by causing a partial oxidation reforming reaction when a reforming action of the fuel by the reformer catalyst becomes possible, heat being generated in said heat and hydrogen generation device by making the fuel burn under a lean air-fuel ratio, characterised in that said electronic control unit is configured to calculate a reference feed fuel amount to be fed to said heat and hydrogen generation device, which is required for making a temperature of the exhaust treatment catalyst rise by exactly a predetermined temperature rise by heat and hydrogen fed from said heat and hydrogen generation device when the exhaust treatment catalyst is not poisoned and does not thermally deteriorate, based on an exhaust gas amount, and said electronic control unit is configured to perform a treatment for restoration from poisoning of said exhaust treatment catalyst if the temperature rise of the exhaust treatment catalyst fails to reach said predetermined temperature rise when fuel of said reference feed fuel amount corresponding to the exhaust gas amount is fed to said heat and hydrogen generation device. an exhaust treatment catalyst arranged in an engine exhaust passage, an electronic control unit, and a heat and hydrogen generation device able to feed only heat or feed heat and hydrogen to the exhaust treatment catalyst to warm up the exhaust treatment catalyst, said heat and hydrogen generation device being provided with a reformer catalyst into which combustion gas of fuel and air is fed, heat and hydrogen being generated in said heat and hydrogen generation device by causing a partial oxidation reforming reaction when a reforming action of the fuel by the reformer catalyst becomes possible, heat being generated in said heat and hydrogen generation device by making the fuel burn under a lean air-fuel ratio, characterised in that said electronic control unit is configured to calculate a reference feed fuel amount to be fed to said heat and hydrogen generation device, which is required for making a temperature of the exhaust treatment catalyst rise by exactly a predetermined temperature rise by heat and hydrogen fed from said heat and hydrogen generation device when the exhaust treatment catalyst is not poisoned and does not thermally deteriorate, based on an exhaust gas amount, and said electronic control unit is configured to perform a treatment for restoration from poisoning of said exhaust treatment catalyst if the temperature rise of the exhaust treatment catalyst fails to reach said predetermined temperature rise when fuel of said reference feed fuel amount corresponding to the exhaust gas amount is fed to said heat and hydrogen generation device.