An object of the present invention is to provide a liquid electrolyte for a fluoride ion battery allowing a reaction between an active material and a fluoride ion. By providing a liquid electrolyte for a fluoride ion battery comprising: a fluoride salt; and a sulfonium compound having a cation in which R1, R2, and R3 (R1, R2, and R3 each independently represent hydrogen, an alkyl group, or a fluoroalkyl group) are bound to the S element, and an anion, wherein the molar ratio of the cation relative to the total of the cation and the fluoride ion (S+/(S++F−)) is 0.96 or more, the present invention achieves the aforementioned object.