A positive electrode active material for nonaqueous electrolyte secondary batteries and production method thereof that are able to improve the stability of positive electrode mixture material pastes used to produce nonaqueous electrolyte secondary batteries, as well as to improve the output characteristics and charge/discharge cycle characteristics of secondary batteries. A method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries includes mixing a fired powder formed of a lithium-metal composite oxide having a layered crystal structure, a first compound which is at least one selected from a group consisting of a lithium-free oxide, a hydrate of the oxide, and a lithium-free inorganic acid salt, and water and drying a mixture resulting from the mixing. The fired powder includes secondary particles formed by agglomeration of primary particles. The first compound reacts with lithium ions in the presence of water to form a second compound including lithium.