Cap Assembly, Secondary Battery Comprising the Same, and Battery Pack

The present invention relates to a secondary battery. The secondary battery comprises: an electrode assembly; a can configured to accommodate the electrode assembly; an electrolyte impregnated into the electrode assembly while being injected into the can; and a cap assembly mounted on an opening of the can, wherein the cap assembly comprises: a top cap in which a top hole is formed to pass vertically; a safety vent which is provided under the top cap and in which a vent hole is formed to pass vertically; and a current interrupt device (CID) filter which is provided under the safety vent, to which a positive electrode tab provided in the electrode assembly is coupled, and in which a CID hole is formed to pass vertically, wherein the CID hole is closed or opened by the positive electrode tab.