An electrolytic capacitor according to the present invention employs a capacitor element wherein an anode foil having an anode internal terminal and a cathode foil having a cathode internal terminal are wound or laminated through a separator. The end of the anode foil faces with the cathode foil through the separator and the surface area of the cathode internal terminal is provided with an enlargement treatment, whereby the small area portion of the cathode foil that faces with the anode foil is eliminated, and the charge/discharge characteristics are thus improved. Furthermore, in the electrolytic capacitor provided with the capacitor element wherein the anode foil having the anode internal terminal and the cathode foil having the cathode internal terminal are wound or laminated through the separator, the capacitor element being impregnated with an electrolyte, the cathode internal terminal is composed of an aluminum material, the surface of the cathode internal terminal is etched and the concentration of iron in the etching layer is less than 300 ppm.