An exhaust treatment catalyst (13) arranged in an engine exhaust passage and a heat and hydrogen generation device (50) are provided. The amount of fuel fed to the heat and hydrogen generation device (50), which is required for making the temperature of the exhaust treatment catalyst (13) rise by exactly a predetermined temperature rise by heat and hydrogen fed from the heat and hydrogen generation device (50) when the exhaust treatment catalyst (13) is not poisoned and does not thermally deteriorate, is calculated based on the amount of exhaust gas. When fuel of the reference feed fuel amount corresponding to the amount of exhaust gas is fed to the heat and hydrogen generation device (50) and the temperature rise of the exhaust treatment catalyst (13) fails to reach the predetermined temperature rise, the treatment for restoration from poisoning of the exhaust treatment catalyst (13) is performed.