It is an object of the present invention to obtain a low-profile electrolytic copper foil with a small surface roughness on the side of the rough surface (the opposite side from the lustrous surface) in the manufacture of an electrolytic copper foil using a cathode drum, and more particularly to obtain an electrolytic copper foil which allows fine patterning, and which is superior in terms of elongation and tensile strength at ordinary temperatures and high temperatures. Furthermore, it is an object of the present invention to obtain a copper electrolytic solution for this purpose. This copper electrolytic solution contains as additives an organo-sulfur compound and a quaternary amine compound with a specific skeleton.