Abstract: A polarization conversion element which is capable of improving the use efficiency of light, and capable of suppressing deterioration is provided. A polarization conversion element includes a main body provided with a light-transmitting member, a polarized light separation layer that transmits first polarized light of light to be incident, and reflects second polarized light, a reflection layer, disposed between the polarized light separation layer and the light-transmitting member, and a retardation layer, disposed on a light emitting end surface of the light-transmitting member, which converts one polarization direction of the first polarized light and the second polarized light into the other polarization direction; and a reflection suppression layer that suppresses reflection from a light emitting surface in the main body, wherein the main body includes an exposure region for exposing at least a portion of a region of a light emitting-side surface in the retardation layer.