An illumination device is provided, including a coherent light source that emits coherent light beam and an optical device that diffuses the coherent light beam. The optical device includes a first diffusion region that diffuses the coherent light beam to illuminate a first area, and a second diffusion region that diffuses the coherent light beam to display predetermined information in a second area. A timing control unit individually controls a light emission timing at which the coherent light source emits the coherent light so that the coherent light is irradiated to the first diffusion region and the second diffusion region, an incident timing at which the coherent light from the coherent light source is incident on the first diffusion region and the second diffusion region, or an illumination timing at which the coherent light diffused by the optical device illuminates the first area and the second area.