Disclosed herein is a secondary battery including an electrode assembly of a cathode/separator/anode structure mounted in a pouch-shaped battery case in a sealed state, wherein a residue portion, which is not sealed (non-sealing residue portion), is defined between a sealing portion of the battery case and the electrode assembly for collecting generated gas, and the non-sealing residue portion is formed by mounting the electrode assembly between upper and lower laminate sheets, at least one of which has a receiving part of a size approximately corresponding to the electrode assembly, sealing three sides of the upper and lower laminate sheets, including two sides where electrode terminals are disposed, among four sides of the upper and lower laminate sheets, injecting an electrolyte in the battery case through the non-sealing portion, and sealing the non-sealing portion such that the resultant sealing portion is spaced a predetermined width from the receiving part.