In a method for recovering an active metal of a lithium secondary battery, a preliminary cathode active material mixture is prepared from a cathode of a waste lithium secondary battery, the preliminary cathode active material mixture is fluidized through oxygen-containing gas within a fluidized bed reactor to form a cathode active material mixture, reductive gas is injected into the fluidized bed reactor to form a preliminary precursor mixture from the cathode active material mixture, and a lithium precursor is recovered from the preliminary precursor mixture.