An aluminum electrolytic capacitor produced by winding an anode foil 11 and a cathode foil 12 via a separator 13 impregnated with a driving electrolyte solution 14, wherein the driving electrolyte solution 14 comprises a polar solvent, at least one electrolyte selected from inorganic acids, organic acids, inorganic acid salts, and organic acid salts, and a random copolymer of polyoxyethylene and polyoxypropylene having a hydroxy group at one end and a hydrogen group at the other end and the separator 13 is formed by overlaying a cellulosic fiber-mixed paper, a cellulosic fiber paper, and a cotton linter. The present invention provides a long-lasting driving electrolyte solution higher in electric conductivity and superior in the chemical self-restoring ability and heat resistance at high temperature, and an aluminum electrolytic capacitor using the same.