According to one embodiment, the secondary battery includes a container, an electrode structure provided in the container and an electrolyte provided in the container. The electrode structure includes a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode. The separator includes an organic fiber layer accumulated on at least one of the positive electrode and the negative electrode. The organic fiber layer has contacts in which the organic fiber intersects with itself. The form of the intersections is changed by a tensile stress.