A control device includes at least one processor, and a memory configured to store a program to be executed by the processor. The processor is configured to acquire an external stimulation applied from an outside to an apparatus, learn an emotion change parameter for changing a simulated emotion of the apparatus in accordance with the acquired external stimulation, acquire the learned emotion change parameter in accordance with the acquired external stimulation, set an emotion parameter indicating the simulated emotion of the apparatus in accordance with the acquired emotion change parameter, and control a behavior of the apparatus in accordance with the set emotion parameter.