The present invention relates to a reflective spatial light modulator enabling improvement of light resistance and prevention of damaging of the liquid crystal layer. The reflective spatial light modulator controls phases of the incident light and a reflected light while reflecting light made incident from a front side, and comprises a liquid crystal layer, a dielectric multilayer film, and a phase shift layer. The liquid crystal layer is filled with a liquid crystal comprised of a light modulating material, and modulates the incident light. The dielectric multilayer film reflects the incident light. The phase shift layer is disposed between the liquid crystal layer and the dielectric multilayer film to shift phases of the incident light and the reflected light at an interface of the liquid crystal layer.