An electrolyte solution for an alkali metal-sulfur-based secondary battery, an alkali metal-sulfur-based secondary battery, and a module containing the alkali metal-sulfur-based secondary battery. The electrolyte solution includes a positive electrode containing a carbon composite material that contains a carbon material and a sulfur-containing positive electrode active material. The carbon material has a pore volume ratio (micropores/mesopores) of 1.5 or higher. The electrolyte solution contains a fluorinated ether represented by the following formula (1): R11—(OR12)n11—O—R13. In the formula, R11 and R13 are the same as or different from each other, and are each an alkyl group optionally containing a fluorine atom, with at least one of R11 or R13 containing a fluorine atom; R12 is an alkylene group optionally containing a fluorine atom; and n11 is 0, 1, or 2.