The present invention relates to a rechargeable battery and, more particularly, to a rechargeable battery for preventing detachment due to deformation of a resin member by strengthening the fixing force of the resin member connecting a bare cell with a protection circuit module.The rechargeable battery according to the present invention includes a bare cell provided with a cap plate; a protection circuit module; and a resin member, wherein the rechargeable battery further includes a reinforcing member composed of a support plate part connected to one side of the cap plate and provided with a rivet through-hole; a resin fixing part integrally formed with one end of the support plate part, and bent at a certain angle in the direction of the protection circuit module and protruded therefrom; and a rivet connecting part fixing the support plate part to the cap plate by perforating the rivet through-hole.According to the present invention, the present invention prevents the resin member from being deformed by the external force as the fixing force is increased by the fixing reinforcing member, and further prevents the resin member from being detached out of the bare cell.