Electrolyte solution and an electrolytic capacitor using it having a low impedance characteristic, having a high withstand voltage characteristic of 100V class, and a high temperature life characteristic is provided. The electrolyte solution containing an aluminum tetrafluoride salt, and a solvent with high boiling point, such as sulfolane, 3-methyl sulfolane, and 2,4-dimethyl sulfolane, and the like are used. The electrolytic capacitor of the present invention has a low impedance characteristic, a high withstand voltage characteristic, and an excellent high temperature life characteristic.