Copper alloy foils are provided having far greater strength and heat resistance than conventional copper foils, and having better productivity, are characterized by a composition comprising, all by weight, from 0.01 to 0.4% Cr, from 0.01 to 0.25% Zr, from 0.02 to 2.0% Zn; and when necessary from 0.05 to 1.8% Fe and from 0.05 to 0.8% Ti; and when further necessary one or more elements selected from the group consisting of Ni, Sn, In, Mn, P, Mg, Al, B, As, Cd, Co, Te, Ag, and Hf in a total amount of from 0.005 to 1.5%; the balance being copper and unavoidable impurities. Inclusions in the copper foil not larger than 10 .mu.m in size, and the inclusions between 0.5 and 10 .mu.m in size number less than 100 pieces/mm.sup.2.