Reflective diffuser plate, display device, projection device, and lighting device

There is provided a reflective diffuser plate to achieve more uniform diffusion angle distribution properties. The reflective diffuser plate is a microlens array reflective diffuser plate including a single lens group positioned on a surface of a transparent base material. There are variations in aperture diameter and radius of curvature that respective single lenses constituting the single lens group have in the single lens group as a whole, and vertex positions of the respective single lenses are located irregularly. A luminance distribution of reflected light of light vertically incident on the single lens group is substantially uniform in a predetermined diffusion angle range. For at least light incident on the single lens group from certain directions, a relation of 0.3≤A/B≤1 holds where A represents a reflection luminance value in the surface normal direction, and B represents a peak reflection luminance value of a diffuse reflection component.