A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The negative electrode contains an active material providing a working potential which is nobler by at least 0.5V than a lithium metal potential. Also, the nonaqueous electrolyte contains an ionic liquid and allyl phosphate represented by chemical formula given below: ##STR00001## where R denotes hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n denotes an integer of 1 to 3.