The present invention comprises: a pre-aging step for aging, at room temperature, a secondary battery comprising a cathode including a cathode active material, an anode including an anode active material, a separator interposed between the cathode and the anode, and an electrolyte (S100); a first charging step for primarily charging the pre-aged secondary battery to an SOC of the secondary battery of 60% or higher (S200); a high-temperature aging step for aging the primarily charged secondary battery at a high temperature (S300); and a room-temperature aging step for aging the high-temperature aged secondary battery at room temperature (S400), wherein the room-temperature aging step comprises a resetting process for charging the secondary battery to the same SOC as in the first charging step.