Hologram data is generated by dividing hologram data generation area, in which hologram data is generated, into a plurality of element sub-areas, computing base hologram data that pertains to an area smaller than the hologram data generation area and that is to form an optical wavefront of an image to be reconstructed, and assigning, as hologram data of the element sub-areas4, hologram data of an entirety or a part of the area to which the base hologram data pertains. Consequently, the amount of operations for generating a hologram pattern in holographic display is reduced.
