An electrolytic solution comprising N-(fluorosulfonyl)-N-(fluoroalkylsulfonyl)imide or di(fluorosulfonyl)imide, from which a residual solvent that affects the properties of the electrolyte solution material is reduced, is provided. A method for producing an electrolyte solution material containing fluorosulfonyl imide salt represented by the following general formula (1) and an electrolyte solution preparation solvent comprises decompressing and/or heating a solution containing the fluorosulfonyl imide salt and the electrolyte solution preparation solvent to volatilize a production solvent for the fluorosulfonyl imide salt. In general formula (1), R1 represents a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms, R2 represents an alkali metal ion.