Positive electrode active material for nonaqueous electrolyte secondary batteries and method for producing positive electrode active material for nonaqueous electrolyte secondary batteries

A positive electrode active material for a nonaqueous electrolyte secondary battery includes a lithium-nickel-cobalt-zinc composite oxide powder that contains lithium (Li); nickel (Ni); cobalt (Co); element M, which is at least one element selected from the group consisting of manganese (Mn), vanadium (V), magnesium (Mg), molybdenum (Mo), niobium (Nb), silicon (Si), titanium (Ti), and aluminum (Al); and zinc (Zn). A molar element ratio (Li:Ni:Co:M) of the lithium-nickel-cobalt-zinc composite oxide powder satisfies Li:Ni:Co:M=z:(1-x-y):x:y (where 0.95≤z≤1.10, 0.05≤x≤0.35, and 0≤y≤0.10); a zinc content with respect to Li, Ni, Co, the element M, and oxygen in the lithium-nickel-cobalt-zinc composite oxide powder is greater than or equal to 0.01 mass % and less than or equal to 1.5 mass %; and at least a part of a surface of the lithium-nickel-cobalt-zinc composite oxide powder includes a zinc solid-solved region where zinc is solid-solved.