An illumination device comprising: 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 illumination device further comprises a scanning unit that scans the optical device with the first coherent light beam and the second coherent light beam from the coherent light source, wherein the optical device is a hologram recording medium, 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, characterized in that the second diffusion region is capable of illuminating the second illumination zone that is at least partially different from the first illumination zone by diffusion of the incident second coherent light beam, the first diffusion region includes a plurality of first element diffusion regions, the first element diffusion regions illuminating respective first partial regions in the first illumination zone by diffusion of the incident first coherent light beam, the first partial regions being respectively illuminated by the first element diffusion regions at least partially different from one another, the second diffusion region also includes a plurality of second element diffusion regions, the second element diffusion regions illuminating respective second partial regions in the second illumination zone by diffusion of the incident second coherent light beam, the second partial regions being respectively illuminated by the second element diffusion regions at least partially different from one another, and an arrangement order of the first element diffusion regions and an arrangement order of the first partial regions do not match, and/or an arrangement order of the second element diffusion regions and an arrangement order of the second partial regions do not match, the first element diffusion regions of the first diffusion region are element hologram areas in which different interference fringe patterns are formed, and the second element diffusion regions of the second diffusion region are element hologram areas in which different interference fringe patterns are formed. 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 illumination device further comprises a scanning unit that scans the optical device with the first coherent light beam and the second coherent light beam from the coherent light source, wherein the optical device is a hologram recording medium, 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, characterized in that the second diffusion region is capable of illuminating the second illumination zone that is at least partially different from the first illumination zone by diffusion of the incident second coherent light beam, the first diffusion region includes a plurality of first element diffusion regions, the first element diffusion regions illuminating respective first partial regions in the first illumination zone by diffusion of the incident first coherent light beam, the first partial regions being respectively illuminated by the first element diffusion regions at least partially different from one another, the second diffusion region also includes a plurality of second element diffusion regions, the second element diffusion regions illuminating respective second partial regions in the second illumination zone by diffusion of the incident second coherent light beam, the second partial regions being respectively illuminated by the second element diffusion regions at least partially different from one another, and an arrangement order of the first element diffusion regions and an arrangement order of the first partial regions do not match, and/or an arrangement order of the second element diffusion regions and an arrangement order of the second partial regions do not match, the first element diffusion regions of the first diffusion region are element hologram areas in which different interference fringe patterns are formed, and the second element diffusion regions of the second diffusion region are element hologram areas in which different interference fringe patterns are formed.