A control apparatus for an internal combustion engine is configured, during a slightly stratified-charge lean-burn operation, to: calculate a basic total fuel injection amount based on a required torque; calculate a compression stroke injection amount based on an ignition delay index value; calculate, as a basic main injection amount, a value obtained by subtracting a compression stroke injection amount from the basic total fuel injection amount; calculate, based on an output value of an in-cylinder pressure sensor, an actual specified combustion index value that represents a main combustion speed or a combustion fluctuation rate; calculate a main injection correction term based on a result of a comparison between a target specified combustion index value or a tolerable specified combustion index value, and the actual specified combustion index value; and calculate a main injection amount by adding the main injection correction term to the basic main injection amount.