An internal combustion engine comprising: an exhaust gas cleaning catalyst (3, 30) being provided in an exhaust passage wherein the exhaust gas cleaning catalyst is configured to clean exhaust gas; a temperature detector configured to detect a temperature of the exhaust gas cleaning catalyst (3, 30); an additives-supply device configured to supply additives to the exhaust gas cleaning catalyst (3, 30), the additives being used to improve the ability of the exhaust gas cleaning catalyst (3, 30) to clean exhaust gas when the temperature of the exhaust gas cleaning catalyst (3, 30) is not more than a predetermined temperature; and an electronic control unit, wherein the electronic control unit is configured to cause the additives supply device to supply the additives to the exhaust gas cleaning catalyst (3, 30) when the temperature of the exhaust gas cleaning catalyst (3, 30), detected by the temperature detector, is not more than the predetermined temperature, wherein the electronic control unit is further configured to execute abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30) based on the ability of the exhaust gas cleaning apparatus to clean exhaust gas of the exhaust gas cleaning catalyst (3, 30), and wherein the temperature is not more than the predetermined temperature when executing abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30), wherein the electronic control unit is configured to reduce an amount of the additives supplied to the exhaust gas cleaning catalyst (3, 30) to less than an amount of the additives supplied to the exhaust gas cleaning catalyst when abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30) at the temperature not more than the predetermined temperature is not executed. an exhaust gas cleaning catalyst (3, 30) being provided in an exhaust passage wherein the exhaust gas cleaning catalyst is configured to clean exhaust gas; a temperature detector configured to detect a temperature of the exhaust gas cleaning catalyst (3, 30); an additives-supply device configured to supply additives to the exhaust gas cleaning catalyst (3, 30), the additives being used to improve the ability of the exhaust gas cleaning catalyst (3, 30) to clean exhaust gas when the temperature of the exhaust gas cleaning catalyst (3, 30) is not more than a predetermined temperature; and an electronic control unit, wherein the electronic control unit is configured to cause the additives supply device to supply the additives to the exhaust gas cleaning catalyst (3, 30) when the temperature of the exhaust gas cleaning catalyst (3, 30), detected by the temperature detector, is not more than the predetermined temperature, wherein the electronic control unit is further configured to execute abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30) based on the ability of the exhaust gas cleaning apparatus to clean exhaust gas of the exhaust gas cleaning catalyst (3, 30), and wherein the temperature is not more than the predetermined temperature when executing abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30), wherein the electronic control unit is configured to reduce an amount of the additives supplied to the exhaust gas cleaning catalyst (3, 30) to less than an amount of the additives supplied to the exhaust gas cleaning catalyst when abnormality diagnosis of the exhaust gas cleaning catalyst (3, 30) at the temperature not more than the predetermined temperature is not executed.