A fuel injection control apparatus of a compression self-ignition internal combustion engine capable of executing, as fuel injection from a fuel injection valve toward the inside of a combustion chamber, at least main injection and auxiliary injection that is performed prior to the main injection, the fuel injection control apparatus comprising: an auxiliary injection time control means that, in a case where the injection time of the auxiliary injection is in a first region whose range is on an angle of delay side of a predetermined injection time, determines, as a target auxiliary injection time, an injection time of the auxiliary injection at which an ignition delay period of fuel injected in the main injection is within a preset allowable ignition delay range and also the ignition delay period is the longest, and in a case where the injection time of the auxiliary injection is in a second region whose range is on an angle of advance side of the first region, determines, as the target auxiliary injection time, an injection time of the auxiliary injection at which the ignition delay period of fuel injected in the main injection is within the preset allowable ignition delay range and also an amount of overlap between a spray of fuel injected in the auxiliary injection and a spray of fuel injected in the main injection is the smallest wherein the injection time of the auxiliary injection is changed during steady operation or deceleration of the internal combustion engine, an ignition delay period when the main injection is executed at each changed injection time is obtained, and whether the injection time of the auxiliary injection is in the first region or the second region is determined based on the obtained ignition delay period, and wherein the determination is performed while setting a region where the ignition delay period of fuel injected in the main injection changes at a substantially constant rate as the pilot injection second region, and a region where the ignition delay period of fuel injected in the main injection cyclically changes as the pilot injection first region. an auxiliary injection time control means that, in a case where the injection time of the auxiliary injection is in a first region whose range is on an angle of delay side of a predetermined injection time, determines, as a target auxiliary injection time, an injection time of the auxiliary injection at which an ignition delay period of fuel injected in the main injection is within a preset allowable ignition delay range and also the ignition delay period is the longest, and in a case where the injection time of the auxiliary injection is in a second region whose range is on an angle of advance side of the first region, determines, as the target auxiliary injection time, an injection time of the auxiliary injection at which the ignition delay period of fuel injected in the main injection is within the preset allowable ignition delay range and also an amount of overlap between a spray of fuel injected in the auxiliary injection and a spray of fuel injected in the main injection is the smallest wherein the injection time of the auxiliary injection is changed during steady operation or deceleration of the internal combustion engine, an ignition delay period when the main injection is executed at each changed injection time is obtained, and whether the injection time of the auxiliary injection is in the first region or the second region is determined based on the obtained ignition delay period, and wherein the determination is performed while setting a region where the ignition delay period of fuel injected in the main injection changes at a substantially constant rate as the pilot injection second region, and a region where the ignition delay period of fuel injected in the main injection cyclically changes as the pilot injection first region.