Provided is an illumination device which has a coherent light source that emits a first coherent light beam and a second coherent light beam, an optical device that diffuses the first coherent light beam to illuminate a first illumination zone and diffuses a wave of the second coherent light beam to illuminate a second illumination zone, and a timing control unit that individually controls incidence timing of the first coherent light beam and the second coherent light beam on the optical device or illumination timing of the first illumination zone and the second illumination zone, wherein the optical device includes a first diffusion region on which the first coherent light beam is incident, and a second diffusion region on which the second coherent light beam is incident, the first diffusion region is capable of illuminating the first illumination zone by diffusion of the incident first coherent light beam.