A color mirror substrate may include a transparent substrate, a plurality of wavelength conversion patterns arranged on the transparent substrate, and a plurality of mirror patterns, ones of the mirror patterns stacked on respective ones of the wavelength conversion patterns. Each wavelength conversion pattern may include a wavelength conversion particle with a quantum dot. In the color mirror display device, a mirror property having a desired color may be implemented. For example, a gold mirror or a black mirror may be implemented by using various types of quantum dots.