NOVELTY - A nonaqueous electrolyte solution is used for nonaqueous electrolyte secondary battery provided with a positive electrode and a negative electrode which occlude/release metal ion, and a separator. The electrolyte solution comprises an electrolyte, a nonaqueous solvent, and a compound (0.01-3 %mass) having two or more isocyanate groups.    USE - Nonaqueous electrolyte solution is used for nonaqueous electrolyte secondary batteries (claimed). Uses include but are not limited to notebook personal computers, pen input personal computers, electronic book players, mobile telephones, portable FAX, portable copiers, portable printer, video movies, liquid-crystal televisions, minidiscs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, backup power supplies, motors, motor vehicles, motorbikes, lighting fixtures, toys, game machine devices, timepieces, electric tools, electronic flashes, cameras, power supplies used for load leveling, and natural energy storage power supplies.    ADVANTAGE - The nonaqueous electrolyte solution provides batteries having excellent low-temperature discharge characteristics and cycle characteristics. The electrolyte solution has excellent chemical stability.    DETAILED DESCRIPTION - A nonaqueous electrolyte solution is used for nonaqueous electrolyte secondary battery provided with a positive electrode and a negative electrode which occlude/release metal ion, and a separator. The electrolyte solution comprises an electrolyte, a nonaqueous solvent, and a compound (0.01-3 %mass) having two or more isocyanate groups and partial structure(s) of formula: -N(-R)-C(=O)- in a molecule.    R=H, or 1-12C organic group configured from hydrogen atom, carbon atom, nitrogen atom, oxygen atom, sulfur atom, phosphorus atom, and/or halogen atom, and optionally having isocyanate group.    An INDEPENDENT CLAIM is included for nonaqueous electrolyte solution secondary battery consisting of the nonaqueous electrolyte solution, a positive electrode, a negative electrode, and a separator.