To provide a technique for simply and easily producing a high-purity difluorophosphate and provide a production process of an electrolytic solution using the obtained difluorophosphate, an electrolytic solution and a secondary battery.A process for producing a difluorophosphate, comprising the following step (1) or (2): (1) reacting (A) at least one member selected from the group consisting of oxoacids, oxoacid anhydrides and oxyhalides of phosphorus with (B) a hexafluorophosphate in the presence of hydrogen fluoride, or (2) reacting at least one halide selected from the group consisting of alkali metal halides, alkaline earth metal halides, aluminum halides and onium halides with difluorophosphoric acid in the presence of a hexafluorophosphate. Also, a nonaqueous electrolytic solution containing the obtained difluorophosphate, and a nonaqueous electrolytic secondary battery containing the nonaqueous electrolytic solution.