Abstract: The invention has for its object to provide a colloidal crystal gel with which any enclosure structure is dispensed with, its production process, and an optical device using the same. The colloidal crystal gel (100) of the invention is characterized in that fine particles (110) are self-organizingly and periodically lined up in a polymer gel (120), and an ion liquid (130) is contained in the polymer gel (120). The production process is characterized in that after the fine particles (110) are self-organizingly and periodically lined up and fixed by the polymer gel (12), the polymer gel is impregnated with the ion liquid (130). The optical device is characterized in that the colloidal crystal gel is used for control of transmission, reflection and diffraction of light and for frequency conversion of light. See FIG. 1.