A fuel injection valve is for injecting fuel to cause combustion in an internal combustion engine. An injection rate adjuster is for adjusting an injection rate of the fuel injected by the fuel injection valve. A control device for the internal combustion engine includes a signal generator, and an outputter. The signal generator generates a command signal to cause the injection rate adjuster to adjust the injection rate based on a parameter, which is to estimate an internal EGR amount in which a part of exhaust gas remains in a cylinder. The outputter outputs the command signal to the injection rate adjuster.