NOVELTY - A nonaqueous electrolyte (5) comprises nonaqueous solvent, electrolyte and combustion inhibitor. The phosphazene compound (X1) having boiling point (x1) ( degrees C) at 1 atmosphere, phosphorus-containing compound (Y1) having boiling point (y1) ( degrees C) at 1 atmosphere, phosphazene compound (X2) having boiling point (x2) ( degrees C) at 1 atmosphere, phosphorus-containing compound (Y2) having boiling point (y2) ( degrees C) at 1 atmosphere, and 1,3,5,2,4,6-triazatriphosphinine derivative (X3) (I) are used as combustion inhibitor. The nonaqueous solvent contains solvent having boiling point of 120 degrees C or less.    USE - Nonaqueous electrolyte is used in secondary battery (claimed). Uses include but are not limited to motor vehicle, electric vehicle, lighting fixture, toy, game machine device, load conditioner, timepiece, electronic flash, camera, shoulder massager, etc.    ADVANTAGE - The nonaqueous electrolyte has excellent flame retardance, and provides secondary battery in which capacity degradation at low temperature conditions and/or large current discharge is/are suppressed, and having excellent cycle characteristics. The secondary battery using positive electrode material containing nickel and/or manganese can be used at high electric potential.    DETAILED DESCRIPTION - A nonaqueous electrolyte comprises nonaqueous solvent, electrolyte and combustion inhibitor. The combustion inhibitor contains phosphazene compound. The nonaqueous solvent contains solvent (A) having boiling point of 120 degrees C or less. The phosphazene compound (X1) having boiling point (x1) ( degrees C) at 1 atmosphere, and phosphorus-containing compound (Y1) having boiling point (y1) ( degrees C) at 1 atmosphere are used as combustion inhibitor. The boiling points (x1,y1) of combustion inhibitor satisfy a relation: x1 less than or equal to 120 less than y1 less than or equal to 220. The phosphazene compound (X2) having boiling point (x2) ( degrees C) at 1 atmosphere, and phosphorus-containing compound (Y2) having boiling point (y2) ( degrees C) at 1 atmosphere are used as combustion inhibitor. The boiling points (x2,y2) of combustion inhibitor, and boiling point (a) ( degrees C) of solvent (A) having low boiling point among the boiling points (x2,y2) of combustion inhibitor and nonaqueous solvent satisfy the relation: x2 less than or equal to a less than y2 less than or equal to a+90. 1,3,5,2,4,6-Triazatriphosphinine derivative (X3) of formula (I) is used as combustion inhibitor. The content of component (X3) is 1-20 wt.% with respect to total electrolyte. The nonaqueous electrolyte contains 20-80 vol.% solvent having boiling point of 100 degrees C or less with respect to total nonaqueous solvent.    R'=C or substituent containing 3 or less C-H bond.    INDEPENDENT CLAIMS are included for the following:    (1) nonaqueous secondary battery, which consists of positive electrode (C), negative electrode (A) and the nonaqueous electrolyte; and    (2) usage method of secondary battery for charging and discharging, which involves using battery at positive electrode electric potential of 4.3 V or more.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic sectional view of the secondary battery. (Drawing includes non-English language text)    Negative electrode electroconductive material (3)    Negative electrode active material (4)    Nonaqueous electrolyte (5)    Negative electrode (A)    Positive electrode (C)