A nonaqueous electrolyte solution for secondary batteries which is an electrolyte solution for secondary batteries obtained by dissolving a lithium salt in a nonaqueous solvent, wherein the nonaqueous solvent is a solvent mainly comprising a lactone compound and the content of hydroxy carboxylic acids in the electrolyte solution is 1 mmol/kg or lower and a secondary battery employing the same are excellent in high-temperature storage characteristics, cycle characteristics, and capacity retention characteristics and in various cell characteristics in a wide temperature range and safety such as firing properties.