A secondary battery includes a container, an electrode assembly received in the container, and an insulator assembly disposed on at least one of an upper end and a lower end of the electrode assembly. When the electrode assembly is moved vertically due to inertia, the insulator assembly is elastically contracted and restored as a reaction to the inertia, thereby reducing pressure generated between an interior surface of the container and the electrode assembly. The insulation assembly may provide insulation effect. It may function as an electrolytic solution flow path.