In combustion control apparatus and method for an internal combustion engine, an exhaust gas purifying section is disposed in an exhaust system of the engine, a determination is made, on the basis of a state of the exhaust gas purifying section, whether a request is issued to switch a combustion mode of the engine to a split retard combustion (predetermined fuel combustion mode) in which a preliminary fuel combustion is carried out at least once at or near to a top dead center and a main fuel combustion to develop a main torque is started after a completion of the preliminary fuel combustion, and the combustion mode of the engine is switched to the split retard combustion when the combustion mode switching request determining section determines that the request is issued and during a transient driving state of the engine.