Zeolite-templated carbon (ZTC), which can be obtained as a negative replica of a zeolite, consists of buckybowllike nanographenes assembled into a three-dimensional regular network. ZTC is characterized not only by this unique framework structure but also by a very large number of carbon edge sites. In this paper, we report that the edge sites of ZTC are easily functionalized by a large amount of quinone groups through electrochemical oxidation unlike general carbonaceous materials, and the quinone-functionalized ZTC shows a high electrochemical capacitance (ca. 300-500 F g-1) in an aqueous electrolyte solution (1M H2SO4) as a result of the large pseudocapacitance derived from a quinone/hydroquinone redox couple. Moreover, ZTC keeps its high capacitance even after thousands of charge-discharge cycles.