Method of manufacturing secondary battery

Disclosed is a method of manufacturing a secondary battery, the method including: manufacturing a pre-lithiation cell including a negative electrode and a lithium metal counter electrode and pre-lithiating the negative electrode by charging the pre-lithiation cell; separating the pre-lithiated negative electrode from the pre-lithiation cell and manufacturing an electrode assembly including the pre-lithiated negative electrode and a positive electrode; impregnating the electrode assembly with an electrolyte; activating the impregnated electrode assembly by performing a first charging the impregnated electrode assembly; removing gas generated in the activation; discharging the activated electrode assembly immediately after removing the gas; and performing a second charging on the discharged electrode assembly.