The invention discloses a secondary battery which detects displacement of a gas discharge part to prevent battery cell swelling, a system for charging a secondary battery, and a method for manufacturing a secondary battery. The present invention relates to a secondary battery which detects a displacement of a gas discharge part to prevent a battery cell swelling, a system for charging the secondary battery, and a method for manufacturing the secondary battery, the secondary battery comprising: a gas discharge part disposed at one end of a sealing part, which seals an electrode assembly, and having an adhesive strength weaker than that of the other adhesive portion of the sealing part to induce a discharge of gas therethrough; and a sensor unit which detects a displacement occurring in thegas discharge part to generate an electrical signal.