Disclosed is a phosphoric acid diester salt which can suppress deterioration of charge-discharge characteristics of a power storage element, and can suppress the rise in internal resistance after storage at high temperature, a production method therefor, a non-aqueous electrolytic solution for a power storage element, and a power storage element. Disclosed is a phosphoric acid diester salt represented by the following chemical formula (1): wherein Mn+ represents a hydrogen ion, an alkali metal ion, an alkali earth metal ion, an aluminum ion, a transition metal ion, or an onium ion; R1 and R2 are different from each other and represent a hydrocarbon group having 1 to 10 carbon atoms, or a hydrocarbon group having 1 to 10 carbon atoms and having at least one of a halogen atom, a heteroatom, and an unsaturated bond; and n represents a valence.