An electrolytic capacitor 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 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, improving the charge/discharge characteristics. 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 includes an aluminum material, the surface of the cathode internal terminal is etched and iron concentration in the etching layer