Abstract: Provided are (1) a nonaqueous electrolytic solution having lithium hexafluorophosphate dissolved in a nonaqueous solvent containing a cyclic carbonate and a linear carbonate, the nonaqueous electrolytic solution including, as a dissolution aid of lithium difluorophosphate, a linear ether compound containing a methoxy group and having a carbon number of 2 or more, a ratio (% by volume/% by mass) of a proportion (% by volume) of the dissolution aid to the total volume of the nonaqueous solvent to an amount (% by mass) of lithium difluorophosphate in the nonaqueous electrolytic solution being 0.1 or more and 5 or less, and lithium difluorophosphate being dissolved in an amount of 1.2% by mass or more at 25° C.; and (2) a lithium secondary battery and a lithium ion capacitor each using the nonaqueous electrolytic solution. The nonaqueous electrolytic solution is excellent in output characteristics and high temperature cyclic property and is capable of suppressing a metal elution amount.