A cable-type secondary battery, includes an electrode assembly including first and second polarity electrodes with a thin and long shape, each having a current collector whose cross-section perpendicular to its longitudinal direction is a circular, asymmetrical oval or polygonal shape, an electrode active material applied onto the surface of the current collector, and a separator or an electrolyte layer interposed between the electrodes; and a cover member surrounding the electrode assembly, wherein the cable-type secondary battery is provided with a first polarity terminal and a second polarity terminal connected to the first polarity electrode and the second polarity electrode, respectively, at the first end of the cable-type secondary battery; a housing cap configured to fix the first and second polarity terminals and cover the first end of the cable-type secondary battery; and a length-adjustable coupling unit at a second end of the cable-type secondary battery.