A secondary battery includes an electrode assembly, a battery case configured to house the electrode assembly and an electrolyte, a lead terminal extending from a coupling section with the electrode assembly, through the battery case and protrudes outside the battery case, and an adhesive layer on the lead terminal having adhesion depending on a reaction of the adhesive layer to the electrolyte. The secondary battery has an improved structure so that an internal short circuit is prevented and stability of the secondary battery is improved.