(1) A lithium salt compound which is composed of a difluorophosphate anion and a lithium cation that has one or more ether compounds selected from among 2, 5, 8, 11-tetraoxadodecane and 2, 5, 8, 11, 14-pentaoxapentadecane as a ligand; (2) a nonaqueous electrolyte solution which is obtained by dissolving an electrolyte salt in a nonaqueous solvent, and which contains the above-described lithium salt compound in the nonaqueous electrolyte solution; (3) a lithium ion secondary battery which is provided with a positive electrode, a negative electrode and the above-described nonaqueous electrolyte solution; (4) a lithium ion capacitor which uses the above-described nonaqueous electrolyte solution; and (5) a method for producing the above-described lithium salt compound, wherein the ether compound(s) and lithium difluorophosphate are brought into contact with each other. A nonaqueous electrolyte solution according to the present invention has excellent high-temperature cycle characteristics and excellent output cha
