A high strength electrolytic copper foil preventing generation of folds, wrinkles, pleats, and breaks during a roll-to-roll (RTR) process, a method of manufacturing the same, and an electrode and a secondary battery which allow high productivity to be secured by being manufactured with such an electrolytic copper foil. The electrolytic copper foil includes a copper film including 99 weight % or more of copper and a protective layer on the copper film, wherein the electrolytic copper foil has a tensile strength of 45 to 65 kgf/mm2.