NONAQUEOUS ELECTROLYTE ENERGY STORAGE DEVICE

A nonaqueous electrolyte energy storage device according to one aspect of the present invention includes: a negative electrode including a negative active material layer; and a nonaqueous electrolyte containing an unsaturated cyclic carbonate and a P—O bond-containing fluorophosphate, in which the negative active material layer has a BET specific surface area of 0.80 m/g or more and 1.5 m/g or less, and the ratio of the content of the unsaturated cyclic carbonate to the total content of the unsaturated cyclic carbonate and the P—O bond-containing fluorophosphate is 0.60 or more and less than 1.0 on a mole basis.