Combustion control apparatus of diesel engine

In a combustion control apparatus of a direct-injection diesel engine, in which a fuel is injected at an early timing with an EGR ratio more than a first predetermined value at pre-mixed combustion area (H) where an engine load is relatively low so as to provide a pre-mixed combustion mode, while a diesel combustion mode is provided with the EGR ratio less than a second predetermined value at diffusion combustion area (D), when the operation of the engine 1 transfers from one of the pre-mixed combustion area (H) and the diffusion combustion area (D) to the other thereof, an opening of the an EGR valve 35 is changed and thereby a fuel injection mode is changed after an actual EGR ratio: EGR becomes a predetermined value: EGR1. When the EGR ratio: EGR is within a certain range (SB5SB13SB15), a follow-up injection (latter-injection) is executed (SB15, SB7) so that combustion thereby may begin at the timing when the main-combustion beginning at around TDC completes mostly. The latter-injection can make smoke produced by the main-injection burn again effectively. As a result, smoke concentration in the exhaust gas can be reduced greatly, and a transient deterioration of the exhaust gas condition at the transition between the operating areas (H), (D) and the like can be avoided.