A secondary battery includes a contact portion on a bottom retainer that contacts a bottom of a case, thus performing a tension function. The secondary battery includes an electrode assembly having a first electrode, a second electrode, and a separator between the first and second electrodes; a case accommodating the electrode assembly therein, having a top and a bottom and an opening in the top of the case; a cap plate closing the opening of the case; a bottom retainer on an upper surface of the bottom of the case, the bottom retainer including a support portion supporting the electrode assembly and at least one contact portion contacting the bottom of the case. As such, the contact portion may absorb external shocks, thus increasing durability and enhancing safety of the secondary battery.