To provide a negative electrode current collector for a lithium ion secondary battery which prevents dissolution of copper in over-discharge and the oxidation of a copper foil in the battery manufacturing process without chromating using hexavalent chromium, and to provide its manufacturing method.

A chromium-based film composed of trivalent chromium is formed on the surface of the copper foil by cathodically electrolyzing the rolled copper foil in an aqueous solution containing trivalent chromium.