A secondary battery includes a retainer and/or an insulation plate having bilateral symmetry, thereby improving work efficiency and productivity. In one or more exemplary embodiments, the secondary battery includes: an electrode assembly; a case receiving the electrode assembly; a cap plate coupled to a top portion of the case and sealing the case; a current collector including a terminal connector positioned between the electrode assembly and the cap plate, and an electrode connector bent from an end of the terminal connector, positioned between the electrode assembly and the case, and having a coupling hole formed therein; an insulation plate positioned on the electrode assembly and coupled to the terminal connector; and a retainer coupled to the electrode connector and including a fixing hook engaged with the coupling hole.