An electrode for electric double-layer capacitor includes a collector with a protective layer containing phosphorous on its surface, and a polarizable electrode layer that is formed on this collector and can adsorb and desorb ions. An amount of a phosphorous compound per unit surface area of the collector, eluted when the collector is immersed into water, is not greater than 1.35 mg/m2 in terms of phosphorous equivalent. An electric double-layer capacitor employs this electrode for at least one of a positive electrode and a negative electrode.