An electrolytic capacitor having a low impedance characteristic, and a high withstand voltage characteristic in the 100V class, provides excellent high temperature life and leakage characteristics. An electrolyte solution containing an aluminum tetrafluoride salt is used. Moreover, a ceramics coating layer or an insulating synthetic resin layer is formed at a contact portion with a sealing component of a rivet or a cathode leading means. Alternatively, a partial cross-linking peroxide butyl rubber with added peroxide as a cross-linking agent to a butyl rubber polymer containing isobutylene, isoprene, and divinylbenzene copolymer is used as the sealing member. The electrolytic capacitor of the present invention has a low impedance characteristic, a high withstand voltage characteristic, and an excellent high temperature life characteristic.