An exhaust purification apparatus for an internal combustion engine according to the present invention includes a heated gas generation apparatus configured to generate heated gas utilizing exhaust gas flowing through an exhaust passage. The heated gas generation apparatus includes a catalyst configured to provide an oxidation function, a fuel supply nozzle, and a heater. An exhaust purification unit is provided downstream of the heated gas generation apparatus. An incoming gas temperature of the exhaust purification unit is detected and estimated. An actual incoming gas temperature being a detected value and an estimated incoming gas temperature both acquired when at least the fuel supply nozzle is actuated are compared with each other. Based on the result of the comparison, the apparatus detects one of poisoning of the catalyst with HC and degradation of the catalyst. Thus, the heated gas generation apparatus is prevented from discharging HC.