To shorten the time required for exposure of a hologram plate.

The exposure device 1 which exposes a hologram plate 9 held at a holder 10 by introducing the object light from an optical unit 241 and the reference light from an optical unit 242 to the hologram plate 9 is provided with mirrors 221 and 222 for scanning the hologram plate with the object light and the reference light. The hologram plate 9 is continuously moved in an X direction by the holder 10 and the irradiation region of the object light and the reference light is scanned together with the movement of the hologram plate 9. As a result, the exposure of one element hologram can be performed while the hologram plate 9 is moved and as a result thereof, the need for starting the exposure after the attenuation of the vibration of the hologram plate 9 is waited by stopping the movement of the hologram plate 9 like heretofore is eliminated and the time requiring for the exposure of the hologram plate 9 can be shortened.