A subject for the invention is to provide an electrolyte solution and a secondary battery which are prevented from causing or suffering battery performance deterioration in high-temperature storage or high-temperature trickle charge.The invention relates to a nonaqueous electrolyte solution for a secondary battery which comprises solute, phosphinic ester compound, and nonaqueous organic solvent containing these, characterized in that the content of the phosphinic ester compound has been regulated to a specific amount based on the total weight of the nonaqueous electrolyte solution.