A hologram generating device characterized in that the hologram generating device comprises: a light source; object light generation means for generating object light in a first polarization direction with the use of a portion of light from the light source; reference light generation means for generating reference light in a second polarization direction intersecting with the first polarization direction at right angle with the use of other portion of light from the light source; irradiation means for irradiating a hologram recording layer of a recording medium with the object light and the reference light; polarization light selecting reflection means placed on the rear surface side of the hologram recording layer for reflecting only either one of the light of the first or the second polarization direction transmitting through the hologram recording layer toward the hologram recording layer; and polarization conversion means placed between the hologram recording layer and the polarization light selecting reflection means converting one of the light of the first or the second polarization direction reflected by the polarization light selecting reflection means to light in a polarization direction intersecting with that in the case of transmitting through the hologram recording layer at right angle, before reaching the hologram recording layer, wherein the irradiation means and the polarization light selecting reflection means are set up such that a reflection type hologram is recorded on the hologram recording layer, the reflection type hologram formed by interference in the hologram recording layer between one of the object light and reference light incident from the rear surface side of the hologram recording layer, having the polarization direction converted by the polarization conversion means and the other of the object light and reference light incident from the front surface side of the hologram recording layer. a light source; object light generation means for generating object light in a first polarization direction with the use of a portion of light from the light source; reference light generation means for generating reference light in a second polarization direction intersecting with the first polarization direction at right angle with the use of other portion of light from the light source; irradiation means for irradiating a hologram recording layer of a recording medium with the object light and the reference light; polarization light selecting reflection means placed on the rear surface side of the hologram recording layer for reflecting only either one of the light of the first or the second polarization direction transmitting through the hologram recording layer toward the hologram recording layer; and polarization conversion means placed between the hologram recording layer and the polarization light selecting reflection means converting one of the light of the first or the second polarization direction reflected by the polarization light selecting reflection means to light in a polarization direction intersecting with that in the case of transmitting through the hologram recording layer at right angle, before reaching the hologram recording layer, wherein the irradiation means and the polarization light selecting reflection means are set up such that a reflection type hologram is recorded on the hologram recording layer, the reflection type hologram formed by interference in the hologram recording layer between one of the object light and reference light incident from the rear surface side of the hologram recording layer, having the polarization direction converted by the polarization conversion means and the other of the object light and reference light incident from the front surface side of the hologram recording layer.