To provide an electrolytic copper foil that has high normal tensile strength, a low decrease in tensile strength after a thermal history, and low concentration of impurities in the copper foil, and to provide a method for producing the electrolytic copper foil.

In the electrolytic copper foil, the concentration of sulfur is 10-50 mass ppm inclusive, lattices having 10 nm gaps are formed with respect to a STEM image obtained at a million times magnification by means of a scanning transmission electron microscope, and when measuring the sulfur concentration with the intersections of the lattices as the measurement points, there are measurement points at which the concentration of sulfur is higher compared to the concentration of sulfur in the copper foil.