A control device 100 for an internal combustion engine includes an in-cylinder oxygen concentration acquisition unit configured to acquire an in-cylinder oxygen concentration, an in-cylinder temperature acquisition unit configured to acquire an in-cylinder temperature, a target in-cylinder temperature acquisition unit configured to acquire a target in-cylinder temperature during main injection based on the in-cylinder oxygen concentration acquired by the in-cylinder oxygen concentration acquisition unit, and an in-cylinder oxygen concentration control unit configured to execute in-cylinder oxygen concentration control for controlling an in-cylinder oxygen concentration during pilot injection performed prior to the main injection based on the difference between the target in-cylinder temperature during the main injection acquired by the target in-cylinder temperature acquisition unit and the in-cylinder temperature acquired by the in-cylinder temperature acquisition unit.