When it is determined that an engine operating condition is in a high-engine load HCCI range (A2) where an engine load is higher than a specified load X1 within a HCCI range A where a compression self combustion is performed, an after-TDC injection F2s is executed at a point T1 when an internal pressure of a combustion chamber drops below a specified pressure Y after the top dead center of an exhaust stroke during a minus valve overlap period NVO during which intake and exhaust valves are both closed. Then, a main injection F2m as a main injection is executed. Accordingly, any improper detonation or deterioration of NOx emission which may be caused by the compression self-ignition combustion in the range where the engine load is relatively high can be prevented.