The nonaqueous electrolyte secondary battery according to one embodiment includes a flat wound electrode body in which a positive plate and a negative plate are wound via a separator and characterized in that the positive plate has a positive core and a positive mixed material layer that is formed on both sides of the positive core, the positive mixed material layer includes a lithium metal composite oxide represented by general formula Li1+xMaO2+b (in the formula, x, a, and b satisfy the conditions x+a=1, −0.2