Positive electrode material for battery and nonaqueous electrolyte secondary battery

A positive electrode active material for a nonaqueous electrolyte secondary battery includes at least a lithium-containing manganese layered composite oxide represented by the general formula Li1-xMn1-yMyO2-δ. The lithium-containing manganese composite oxide is deficient in lithium with respect to the stoichiometric composition of a layered crystal structure represented by the general formula LiMeO2. Part of Mn is replaced by a substitute metal such as Co, Ni, Fe, Al, Ga, In, V, Nb, Ta, Ti, Zr, Ce or Cr.