Abstract: Provided is a non-aqueous electrolyte solution that achieves a favorable balance between suppressing an increase in resistance and improving metallic Li precipitation resistance in an embodiment that contains LiPO2F2. The non-aqueous electrolyte solution disclosed here is used in a non-aqueous electrolyte secondary battery, and contains lithium difluorophosphate and a Cs cation-containing compound. When the total amount of the non-aqueous electrolyte solution is taken to be 100 mass %, the content of the lithium difluorophosphate is 1.0 mass % or less and the content of the Cs cation-containing compound is 0.1 to 0.5 mass %.