A basic injection timing (InjO) is set, and an intermediate time (.DELTA.Inj) is set based on rotational speed of an engine and fuel injection pulse time in a fuel injector. A fuel injection starting timing (.theta.) is set according to the sum or difference of the basic injection timing and the intermediate time. As a result, mixture is introduced into a vortex controlled combustion chamber so that a rich mixture is distributed to the upper portion of the combustion chamber near the ignition plug to provide satisfactory stratified combustion.