An electrolyte for an electrolytic capacitor which is high in electrolytic conductivity, excellent in heat stability and high in withstand voltage. An electrolyte for an electrolytic capacitor comprising a tetrafluoroaluminate ion; and an electrolyte for an electrolytic capacitor containing a salt and a solvent, characterized in that electrolytic conductivity X (mScm.sup.-1) at 25.degree. C. and withstand voltage Y (V) of a capacitor satisfy the relationships of formulae (I): Y.gtoreq.-7.5X+150, and X.gtoreq.4, Y>0.