To provide a nonaqueous electrolyte secondary battery with good load characteristics and high safety.

A nonaqueous electrolyte secondary battery has a positive electrode, a negative electrode, and a nonaqueous electrolyte. Polymer phosphate having two or more phosphate groups in a molecule is contained in the electrolyte. The polymer phosphate having the structural formula represented by formula is preferable. (In formula, (n) is an integer of more than 0, R1, R2, R4, R5, and R7 represent a hydrocarbon group having 1-6 carbon atoms, a halogenated hydrocarbon group, or an aromatic group, R3, R6 represent a hydrocarbon group having 3 or less carbon atoms or a halogenated hydrocarbon group, and the number of total carbon atoms of organic groups of R1-R7 is 20 or less.