NOVELTY - A nonaqueous electrolyte secondary battery has a negative electrode, a positive electrode, and nonaqueous electrolyte interposed between electrodes. The negative electrode contains titanium-containing oxide as negative electrode active material, and the positive electrode contains spinel-type lithium manganate (I), and a cobalt-containing compound and/or lithium-transition metal composite oxide having layered rock salt structure, as positive electrode active material. The nonaqueous electrolyte contains 0.01-5 wt.% organic compound with respect to 100 wt.% nonaqueous electrolyte.    USE - Nonaqueous electrolyte secondary battery is used for forming assembled batteries (claimed). Uses include but are not limited to portable apparatus, hybrid motor vehicles, electric vehicles, and domestic electrical storage.    ADVANTAGE - The nonaqueous electrolyte secondary battery has suppressed gas-evolution at the time of charging/discharging cycle, excellent cycle stability and charge rate characteristics, and improved safety.    DETAILED DESCRIPTION - A nonaqueous electrolyte secondary battery has a negative electrode, a positive electrode, and nonaqueous electrolyte interposed between electrodes. The negative electrode contains titanium-containing oxide as negative electrode active material, and the positive electrode contains spinel-type lithium manganate of formula: Li1+xMyMn2-x-yO4, and a cobalt-containing compound and/or lithium-transition metal composite oxide having layered rock salt structure, as positive electrode active material. The weight (A) of spinel-type lithium manganate and weight (B) of cobalt-containing compound and/or lithium-transition metal composite oxide having a layered rock salt structure satisfy the relation: 0.01 less than or equal to (B/(A+B)) less than or equal to 0.1. The nonaqueous electrolyte contains 0.01-5 wt.% compound chosen from oxalic acid skeleton-containing organic compound, isocyanate group-containing organic compound, lithium salt of sulfonic acid skeleton-containing organic compound and succinic acid anhydride compound having side chain with 3 or more carbon atoms with respect to 100 wt.% nonaqueous electrolyte.    x=0-0.2;    y=0-0.6 (excluding 0);and    M=element chosen from groups 2-13 of periodic table.