An electrode active material including a lithium-transition metal complex oxide having a layered rock salt structure or spinel structure and a fluorine and nitrogen introduced therein. Also disclosed is an electrode active material production method including a nitrogen introduction step of synthesizing a lithium-transition metal complex oxide (c) having a layered rock salt structure or spinel structure and a fluorine and nitrogen introduced therein, by firing a material composition including a lithium-transition metal complex oxide (a) having a fluorine introduced therein and a nitriding agent (b) being represented by the formula (1) and being solid or liquid at ordinary temperature.