An electrolyte for a lithium-sulfur battery and the lithium-sulfur battery including the electrolyte, more particularly, an electrolyte for the lithium-sulfur battery including lithium salt, an organic solvent and an additive, wherein the additive includes an alkali metal salt-type ionomer. The electrolyte for the lithium-sulfur battery improves the migration characteristics of lithium ions and thus improves the capacity and life characteristics of the lithium-sulfur battery by including a polymer containing the alkali metal ion as an additive.