Disclosed is a method for producing a lithium difluorobis(oxalato)phosphate solution, which is characterized by that lithium hexafluorophosphate and oxalic acid are mixed together in a nonaqueous solvent, in a manner that the molar ratio of lithium hexafluorophosphate to oxalic acid falls within a range of 1:1.90 to 1:2.10, and furthermore silicon tetrachloride is added to this, in a manner that the molar ratio of lithium hexafluorophosphate to silicon tetrachloride falls within a range of 1:0.95 to 1:1.10, thereby conducting a reaction. The lithium difluorobis(oxalato)phosphate solution produced by this method has low contents of chlorine compounds and free acids. Therefore, it can become an additive that is effective for improving performance of nonaqueous electrolyte batteries.