a method of manufacturing the rolled copper foil by a process which comprises hot rolling an ingot repeating cold rolling and annealing alternately , and finally cold rolling the work to a foil , the annealing immediately preceding the final cold rolling being performed under conditions that enable the annealed recrystallized grains to have a mean grain diameter of not greater than 20 μm , the reduction ration of the final cold rolling being beyond 90 . 0 %, whereby excellent flex fatigue property and adequate softening property are achieved .