A copper alloy foil consisting of a rolled copper alloy foil containing at least one or more elements selected among Ag, Sn, Cr, Zr, Zn, Ni, Si, Mg, and Ti in a total amount of 0.03 to 5 wt % and remnant Cu and unavoidable impurities and having a roughened surface of fine copper particles, said roughened surface having craters in which a number of craters is 0.5 craters/mm2 or less, said roughened surface being produced by a process comprising the steps of subjecting a rolled copper alloy foil to roughening plating with a plating bath consisting of copper sulfate having a Cu equivalent of 1 to 50 g/L, nickel sulfate having a Ni equivalent of 1 to 50 g/L, 1 to 150 g/L of sulfuric acid, and one or more additives selected among sodium octyl sulfate, sodium decyl sulfate, and sodium dodecyl sulfate under the conditions of a temperature of 20 to 50° C. and a current density of 10 to 100 A/dm2.