The present invention relates to a method for manufacturing a secondary battery and a pre-degassing device for manufacturing a secondary battery. The method for manufacturing the secondary battery comprises: an accommodation process of accommodating an electrode assembly in an accommodation part formed inside a battery case to form a cell; an electrolyte injection process of injecting an electrolyte into the accommodation part of the battery case; a primary aging process of elapsing a predetermined time so that the electrode assembly is impregnated into the electrolyte; a primary charging process of primarily charging and discharging the cell; a pre-degassing process of pressing the battery case to discharge a gas inside the electrode assembly to the outside of the electrode assembly; and a secondary aging process of elapsing a predetermined time so that the electrode assembly is impregnated into the electrolyte, wherein, in the pre-degassing process, the battery case is pressed while applying heat to the battery case.