A carbon electrode includes a substrate, and a conductive carbon layer disposed at an upper side of the substrate and having an sp2 bond and an sp3 bond. On an upper surface of the conductive carbon layer, the concentration ratio of oxygen to carbon is 0.07 or more. The ratio of a number of sp3 bonded carbon atoms to the sum of a number of sp2 bonded carbon atoms and the number of sp3 bonded carbon atoms is 0.35 or more.