NOVELTY - A nonaqueous electrolyte solution comprises formyl derivative (I), and a compound chosen from cyclic carbonate compound which has unsaturated bond, cyclic carbonate compound which has fluorine atom, nitrile compound, isocyanate compound, aromatic hydrocarbon, fluorinated benzene compound, compound which has silicon-silicon bond (excluding aliphatic substituent having unsaturated bond), compound which has sulfur-oxygen bond, compound (II), monofluorophosphate and difluorophosphate. The nonaqueous electrolyte solution is used for non-aqueous electrolyte solution secondary battery.    USE - Electrolyte solution is used for nonaqueous electrolyte solution secondary battery (claimed). Uses include but are not limited to notebook personal computer, pen input personal computer, mobile personal computer, electronic book player, portable copy, portable printer, headphones stereo, backup power supply, motor vehicle and lighting fixture.    ADVANTAGE - The nonaqueous electrolyte secondary battery comprising nonaqueous electrolyte solution has improved cyclic characteristics and load characteristics, and high energy density, with suppressed generation of gas and deterioration.    DETAILED DESCRIPTION - A nonaqueous electrolyte solution comprises formyl derivative of formula (I), and a compound chosen from cyclic carbonate compound which has unsaturated bond, cyclic carbonate compound which has fluorine atom, nitrile compound, isocyanate compound, aromatic hydrocarbon, fluorinated benzene compound, compound which has silicon-silicon bond (excluding aliphatic substituent having unsaturated bond), compound sulfur-oxygen bond (S=O), compound of formula (II), monofluorophosphate and difluorophosphate. The nonaqueous electrolyte solution is used for nonaqueous electrolyte solution secondary battery provided with positive electrode which has positive electrode active material which is optionally occlude/release a metal ion, and negative electrode which has a negative electrode active material which is optionally occlude/release a metal ion.    R1-R6=H, fluoro, alkyl, alkenyl, alkynyl or aryl;    M=1-6C hydrocarbyl optionally substituted by group (XIII) transition metal, group (XIV) transition metal, group (V) element, or hetero atom;    a,b=1-3;    l=b divide by a;    m=1-4;    n=1-8;    t=0-1;    p=0-3;    q=0-2;    r=0-2;    R21=halo, 1-20C hydrocarbyl (optionally substituted by hetero atom), or X3R24;    R22=direct bond or 1-6C hydrocarbyl which is optionally substituted by hetero atom;    X1-X3=O, S, or NR25;    R23 and R21, or R22 in R24 or R25=H or 1-10C hydrocarbyl which optionally substituted by hetero atom, in which two or more R23-R25 bonded to form ring;and    Y'1,Y'2=C, S, or Si.    (i) When M is group (XIII) transition metal or table, group (XIV) transition metal or group (XV) element, Za+ is metal ion, proton or onium ion; (ii) When Y'1 or Y'2 is C or Si, q or r is 0 or 1, respectively; and (iii) When Y'1 or Y'2 is S, q or r is 2, respectively. An INDEPENDENT CLAIM is included for nonaqueous electrolyte solution secondary battery.