A lithium-sulfur battery comprising a separator in which an adsorption layer including a radical compound having a nitroxyl radical site is formed, and in particular, to a lithium-sulfur battery suppressing elution of lithium polysulfide by using an adsorption layer including a radical compound having a nitroxyl radical site and optionally a conductive material on at least one surface of a separator. In the lithium-sulfur battery, elution and diffusion may be prevented by a radical compound having a nitroxyl radical site, a stable radical compound, adsorbing lithium polysulfide eluted from positive electrode, and in addition thereto, electrical conductivity is further provided to provide a reaction site of a positive electrode active material, and as a result, battery capacity and lifetime properties are enhanced.