A thin pouch battery, which is used as a power source of a portable electronic apparatus, a portable electronic terminal, or the like, includes protrusions, into which an electrode group is inserted, formed in both a laminate film on the upper side and a laminate film on the lower side. Then, concentrically concave and convex wave shapes (concentric crest ridges or trough furrows) are formed on the top surface of each of the protrusions such that the protrusion can extend or shrink in any direction, or the protrusion has a side surface that is gradually inclined and a wave shape is formed on the side surface of the protrusion.