A reflective spatial light modulator includes an electro-optic crystal having an input surface to which input light is input and a rear surface opposing the input surface, a light input/output unit being disposed on the input surface of the electro-optic crystal and having a first electrode through which the input light is transmitted, a light reflection unit including a substrate including a plurality of second electrodes and an adhesive layer for fixing the substrate to the rear surface and being disposed on the rear surface of the electro-optic crystal, and a drive circuit applying an electric field between the first electrode and the plurality of second electrodes.