Control device of illumination device

A control device of an illumination device capable of controlling a diffusion degree of light emitted from a light source, the control device comprising:

• a detection device provided with a diffusion degree adjustment region of the illumination device in a detection region where a plurality of detection elements are provided;
• and
• a processing device configured to control a diffusion degree change amount of the illumination device in accordance with a movement amount of a touch detection position in the diffusion degree adjustment region, wherein
• the processing device
• calculates the diffusion degree change amount corresponding to a first directional component of the movement amount of the touch detection position in the diffusion degree adjustment region, and
• calculates the diffusion degree change amount corresponding to a second directional component of the movement amount of the touch detection position in the diffusion degree adjustment region, the second directional component being different from the first directional component.