The present invention relates to a cable-type secondary battery having a horizontal cross section of a predetermined shape and extending longitudinally, comprising: a core for supplying lithium ions, which comprises an electrolyte; an inner electrode, comprising an open-structured inner current collector surrounding the outer surface of the core for supplying lithium ions, an inner electrode active material layer formed on the surface of the inner current collector, and an electrolyte-absorbing layer formed on the outer surface of the inner electrode active material layer; a separation layer surrounding the outer surface of the inner electrode to prevent a short circuit between electrodes; and an outer electrode surrounding the outer surface of the separation layer and comprising an outer electrode active material layer and an outer current collector.