To provide a method of manufacturing a positive electrode active material for a nonaqueous electrolyte secondary battery that prevents oxidation and degradation of the electrolyte when charged or discharged, while improving the capacity of a secondary battery.

The manufacturing method brings gas containing fluorine gas with partial pressure of 0.5 to 50 kPa into contact with a transition metal positive electrode active material containing lithium, and includes fluorine atom in a part of the transition metal positive electrode active material containing lithium.