To prevent the corrosion of an aluminum electrode due to chlorine ion by a method, wherein boric acid or borate and polyphosphoric acid are added and dissolved into the electrolyte formed by dissolving organic acid or organic acid salt using ethylene glycol as the main solvent, and then bisethyleneglycol ammonium borate is added and dissolved.

An electrolyte for driving an electrolytic capacitor is formed by adding and dissolving boric acid or borate and polyphosphoric acid into the electrolyte, formed by dissolving organic acid or organic acid salt using ethylenglycol as the main solvent, and furthermore, biethyleneglycol ammonium borate is added and dissolved. At this point, the electrolyte is constituted by adding boric acid or boric acid salt of 2 to 10 wt.%, polyphosphoric acid of 0.005 to 0.5 wt.% and bisethyleneglycol ammonium borate of 10 to 20 wt.% to the electrolyte formed by dissolving an organic acid or organic acid salt of 2 to 10 wt.% using ethyleneglycol as main solvent. Moreover, the carbon number of the organic acid or the organic acid salt is set at 10 to 12.