EXHAUST PURIFICATION SYSTEM OF INTERNAL COMBUSTION ENGINE AND EXHAUST PURIFICATION METHOD

An exhaust purification system of an internal combustion engine comprises: an adsorbent adsorbing HC and NOx in exhaust gas, a catalyst removing HC and NOx, an air-fuel ratio control part configured to control an air-fuel ratio of exhaust gas discharged from an engine body of the internal combustion engine to the exhaust passage, and a temperature calculating part configured to calculate a temperature of the adsorbent. At the adsorbent, a desorption temperature of HC is higher than a desorption temperature of NOx. The air-fuel ratio control part is configured to make the air-fuel ratio a stoichiometric air-fuel ratio when a temperature of the adsorbent is in the vicinity of the desorption temperature of NOx, then make the air-fuel ratio leaner than the stoichiometric air-fuel ratio when the temperature of the adsorbent reaches the vicinity of the desorption temperature of HC.