Disclosed herein is a secondary battery constructed in a structure in which an electrode assembly having a cathode/separator/anode arrangement is mounted in a battery case made of a laminate sheet including a resin layer and a metal layer, electrode tabs of the electrode assembly are coupled to corresponding electrode leads, and the electrode assembly is sealed in the battery case while electrode leads are exposed to the outside of the battery case, wherein a protective film is attached to coupling regions between the electrode tabs and the electrode leads for sealing the coupling regions between the electrode tabs and the electrode leads. The secondary battery according to the present invention is constructed in a structure in which the coupling regions are sealed by the protective film, unlike a conventional secondary battery constructed in a structure in which the coupling regions between the electrode tabs and the electrode leads are exposed in the battery case. As a result, the electrode leads are protected from external impacts, such as falling of the battery. Consequently, no internal short circuit occurs, and therefore, the safety of the battery is increased.