An electric copper foil is applied as a current collector for a lithium secondary battery, and in a peak curve with respect to a (111) plane appearing on an X-ray diffraction analysis graph (a graph in which an X-axis variable is a diffraction angle 2θ and a Y-axis variable is an intensity of a diffracted X-ray) in a state where the electric copper foil is not thermally treated, the electric copper foil has a full width at half maximum (FWHM) of 0.08 or above and 0.15 or below.