A copper electrolytic solution for obtaining a low profile electrolytic copper foil having reduced surface roughness on the rough surface side (side opposite to glossy surface) in the production of an electrolytic copper foil by the use of a cathode drum. In particular, a copper electrolytic solution for obtaining an electrolytic copper foil that excels in high-frequency transmission loss characteristics, enabling realization of fine pattern and excels in elongation and tensile strength at ordinary and high temperatures. The copper electrolytic solution comprises, as additives, (A) at least one quaternary amine salt selected from among quaternary amine salts (a) being products of reaction between epichlorohydrin and an amine compound mixture consisting of a secondary amine compound and a tertiary amine compound and polyepichlorohydrin quaternary amine salts (b) and (B) an organic sulfur compound.