The present invention provides a secondary battery including an insulating plate which enables easy gas discharge and is not broken at high temperature. For this purpose, disclosed is a secondary battery comprising: a case including a space therein through an opening; at least one electrode assembly inserted into the space of the case; an insulating plate formed at an upper part of the electrode assembly; and a cap plate which is coupled to the opening of the case and includes a vent, at least one region of which has a thinner thickness than other regions, wherein the insulating plate includes a plurality of gas discharge holes disposed at a region corresponding to the vent.