The present invention relates to a secondary battery enabling enhanced safety in case of an external short circuit. According to one example, the secondary battery comprises: an electrode assembly; a case for accommodating the electrode assembly; and a cap assembly coupled to the top of the case. The cap assembly comprises: a cap-up; a safety vent provided below the cap-up; a cap-down provided below the safety vent and having a through hole and a gas discharge hole; an insulator provided between the safety vent and the cap-down; a sub-plate provided below the cap-down; and a solder member for electrically connecting the safety vent and the sub-plate. The safety vent and the sub-plate are electrically connected by means of soldering.