A cap assembly of a cylindrical rechargeable battery includes an integrated gasket obtained by integrating a first gasket covering a top cap, a PTC element, and a safety vent and a second gasket covering a CID. The rechargeable battery including the cap assembly has the advantages of increasing a contact area between a safety vent and a gasket by integrating the existing dual-gasket structure to thereby increase a sealing effect, increasing a short circuit reactivity of the CID by freely changing the gasket structure according to the diameter of the current interrupting member to thereby improve stability, simplify components, and reduce a production unit cost.