The invention provides a hologram generating device and a hologram generating method that allows the generation of a hologram for reproducing an easily observable three-dimensional image without restrictions on object sizes. The hologram generating device includes an object light generation means, a reference light generation means, an irradiation means, a polarization light selecting reflection means, and a polarization conversion means, wherein the one of the object light and the reference light incident from the rear surface is made to interfere with the other of the object light and reference light incident from the front surface in the hologram recording layer to record a reflection type hologram on the hologram recording layer.