A nonaqueous electrolyte secondary battery includes a nonaqueous electrolyte and a positive electrode including an active material containing lithium composite oxide powder, the lithium composite oxide powder includes secondary particles, exhibits a peak intensity ratio satisfying the following formula (4), satisfies the following formula (5), and has a particle distribution wherein a particle diameter at a volumetric cumulative frequency of 90% (D90) falls within the range of 10 to 25 m, and the nonaqueous electrolyte contains a sultone compound including a ring having at least one double bond; 2.ltoreq.(I.sub.003/I.sub.104)<5 (4) 0.95.ltoreq.(X.sub.Li/X.sub.M).ltoreq.1.02. (5)