To provide a method for manufacturing a lithium secondary battery, characterized by having: a processing lithium secondary battery preparing step for preparing a processing lithium secondary battery that has a positive electrode layer containing LiFePO4 as a positive-electrode active material, a negative electrode layer containing a carbon material as a negative-electrode active material, and nonaqueous electrolyte solution containing LiPF6 and LiBOB; and a film forming step of performing a charging process on the processing lithium secondary battery until a voltage of the processing lithium secondary battery falls within a high voltage range in which a film of an oxidative decomposition product of a BOB anion contained in the LiBOB is formed on a surface of the positive-electrode active material.