A secondary battery includes an electrode assembly including a positive electrode plate and a negative electrode plate; a can accommodating the electrode assembly; and a cap assembly having a cap plate sealing the opening of the can, a terminal plate on one side of the cap plate and being electrically connected to the negative electrode plate, and an insulation plate located between the cap plate and the terminal plate, the insulation plate including a bottom plate, and first and second long side walls and first and second short side walls extending from the bottom plate and respectively encompassing opposing long sides and opposing short sides of the terminal plate, wherein the first and second long side walls have recessed regions, and wherein the terminal plate is configured to contact the can at the recessed regions when the can is deformed by compression.