Provided is an electrolytic solution suitable for use in a 100 WV electrolytic capacitor having low inductance at low temperatures and high durability in high-temperature use conditions. This electrolytic solution for an electrolytic capacitor contains: a mixed organic solvent including sulfolane and [gamma]-butyrolactone; water; an electrolyte selected from the group consisting of a quaternized pyridinium salt and a quaternized imidazolinium salt of carboxylic acid; boric acid; and mannitol; and has a mass ratio of boric acid and mannitol in the range of 1:1.2-1:1.6, and a total amount of boric acid and mannitol of 10.0-14.5 mass percent of the total electrolytic solution, the water content being 1.5-2.0 mass percent of the total electrolytic solution.