A fuel injection control apparatus of a compression ignition type internal combustion engine, wherein fuel is injected into a cylinder and combusted by self-ignition, the apparatus comprising: a controller configured to control an injector that injects the fuel into the cylinder so as to perform pre-stage injection and post-stage injection as fuel injection during one cycle, wherein the controller: adjusts timing of the pre-stage injection, an injection amount of the pre-stage injection, timing of the post-stage injection, and an injection amount of the post-stage injection so that a value obtained by differentiating a cylinder pressure by a time or a value obtained by differentiating the cylinder pressure by a crank angle during one cycle has a pre-stage peak by combustion of the fuel supplied by the pre-stage injection and a post-stage peak by combustion of the fuel supplied by the post-stage injection; and adjusts an interval Δt0 between the timing of the pre-stage injection and the timing of the post-stage injection so that an interval Δt1 between the timing of the pre-stage peak and the timing of the post-stage peak approximately satisfies a condition such that Δt1 = 0.5/f0, wherein f0 is a frequency at which a combustion noise level becomes the maximum when fuel injection is performed so that a single peak equal to or more than a set value is derived from the value obtained by differentiating the cylinder pressure by a time or the value obtained by differentiating the cylinder pressure by a crank angle during one cycle, and wherein f0 is a frequency at which a combustion noise level becomes the maximum when fuel injection is performed, the frequency f0 is obtained based on the combustion noise spectrum by a machine experiment in which a one-stage combustion was performed so that the peak value equal to or more than the set value from the value obtained by differentiating the cylinder pressure by a time or the value obtained by differentiating the cylinder pressure by a crank angle during on cycle, is one. a controller configured to control an injector that injects the fuel into the cylinder so as to perform pre-stage injection and post-stage injection as fuel injection during one cycle, wherein the controller: adjusts timing of the pre-stage injection, an injection amount of the pre-stage injection, timing of the post-stage injection, and an injection amount of the post-stage injection so that a value obtained by differentiating a cylinder pressure by a time or a value obtained by differentiating the cylinder pressure by a crank angle during one cycle has a pre-stage peak by combustion of the fuel supplied by the pre-stage injection and a post-stage peak by combustion of the fuel supplied by the post-stage injection; and adjusts an interval Δt0 between the timing of the pre-stage injection and the timing of the post-stage injection so that an interval Δt1 between the timing of the pre-stage peak and the timing of the post-stage peak approximately satisfies a condition such that Δt1 = 0.5/f0, wherein f0 is a frequency at which a combustion noise level becomes the maximum when fuel injection is performed so that a single peak equal to or more than a set value is derived from the value obtained by differentiating the cylinder pressure by a time or the value obtained by differentiating the cylinder pressure by a crank angle during one cycle, and wherein f0 is a frequency at which a combustion noise level becomes the maximum when fuel injection is performed, the frequency f0 is obtained based on the combustion noise spectrum by a machine experiment in which a one-stage combustion was performed so that the peak value equal to or more than the set value from the value obtained by differentiating the cylinder pressure by a time or the value obtained by differentiating the cylinder pressure by a crank angle during on cycle, is one. adjusts timing of the pre-stage injection, an injection amount of the pre-stage injection, timing of the post-stage injection, and an injection amount of the post-stage injection so that a value obtained by differentiating a cylinder pressure by a time or a value obtained by differentiating the cylinder pressure by a crank angle during one cycle has a pre-stage peak by combustion of the fuel supplied by the pre-stage injection and a post-stage peak by combustion of the fuel supplied by the post-stage injection; and adjusts an interval Δt0 between the timing of the pre-stage injection and the timing of the post-stage injection so that an interval Δt1 between the timing of the pre-stage peak and the timing of the post-stage peak approximately satisfies a condition such that Δt1 = 0.5/f0, wherein f0 is a frequency at which a combustion noise level becomes the maximum when fuel injection is performed so that a single peak equal to or more than a set value is derived from the value obtained by differentiating the cylinder pressure by a time or the value obtained by differentiating the cylinder pressure by a crank angle during one cycle, and wherein f0 is a frequency at which a combustion noise level becomes the maximum when fuel injection is performed, the frequency f0 is obtained based on the combustion noise spectrum by a machine experiment in which a one-stage combustion was performed so that the peak value equal to or more than the set value from the value obtained by differentiating the cylinder pressure by a time or the value obtained by differentiating the cylinder pressure by a crank angle during on cycle, is one.