A lithium-sulfur secondary battery comprising: a positive electrode or a negative electrode containing a sulfur-based electrode active material including at least one of elemental sulfur or lithium polysulfide; an electrolyte solution containing an ether compound represented by the following formula: [Formula 1] R 1 -(OCHR 3 CH 2) x -OR 2 wherein R 1 and R 2 are each independently selected from a group consisting of an alkyl group having 1 to 9 carbon atoms which may be substituted with fluorine, a phenyl group which may be substituted with a halogen atom, and a cyclohexyl group which may be substituted with a halogen atom, wherein R 1 and R 2 may be combined together to form a ring; R 3 each independently represents H or CH 3; and x represents 0 to 10, a lithium salt, and a solvent, wherein at least a part of the ether compound and the lithium salt form a complex; and a counter electrode which is a counter electrode of the positive electrode or the negative electrode and contains the lithium, an alloy containing the lithium, carbon, or an active material which intercalates and deintercalates a lithium ion, characterized in that the solvent is a hydrofluoroether, which has a hydrophobicity, is completely mixed with the complex, and does not chemically react with the lithium and the lithium polysulfide, Li 2 S n: 1 ≤ n ≤ 8. a positive electrode or a negative electrode containing a sulfur-based electrode active material including at least one of elemental sulfur or lithium polysulfide; an electrolyte solution containing an ether compound represented by the following formula: [Formula 1] R 1 -(OCHR 3 CH 2) x -OR 2 wherein R 1 and R 2 are each independently selected from a group consisting of an alkyl group having 1 to 9 carbon atoms which may be substituted with fluorine, a phenyl group which may be substituted with a halogen atom, and a cyclohexyl group which may be substituted with a halogen atom, wherein R 1 and R 2 may be combined together to form a ring; R 3 each independently represents H or CH 3; and x represents 0 to 10, a lithium salt, and a solvent, wherein at least a part of the ether compound and the lithium salt form a complex; and a counter electrode which is a counter electrode of the positive electrode or the negative electrode and contains the lithium, an alloy containing the lithium, carbon, or an active material which intercalates and deintercalates a lithium ion, wherein R 1 and R 2 are each independently selected from a group consisting of an alkyl group having 1 to 9 carbon atoms which may be substituted with fluorine, a phenyl group which may be substituted with a halogen atom, and a cyclohexyl group which may be substituted with a halogen atom, wherein R 1 and R 2 may be combined together to form a ring; R 3 each independently represents H or CH 3; and x represents 0 to 10, a lithium salt, and a solvent, wherein at least a part of the ether compound and the lithium salt form a complex; and a counter electrode which is a counter electrode of the positive electrode or the negative electrode and contains the lithium, an alloy containing the lithium, carbon, or an active material which intercalates and deintercalates a lithium ion, characterized in that the solvent is a hydrofluoroether, which has a hydrophobicity, is completely mixed with the complex, and does not chemically react with the lithium and the lithium polysulfide, Li 2 S n: 1 ≤ n ≤ 8.