A lithium based battery includes a cell structure group formed by stacking unit cells each including a positive electrode, a negative electrode, and a separator interposed therebetween, or formed by repeatedly folding or winding an integral body of the unit cells; a battery container for containing the cell structure group; and an electrolyte, which is poured in the battery container after the cell structure group is contained in the battery container. The outer peripheral surface of the battery container is covered with an ion impermeable and extensible high polymer sheet having a tensile elongation percentage of 1% or more. With this configuration, even if there happens such a severe accident that nail pieces the battery or the battery is crashed, it is possible to prevent a large short-circuit current from flowing between the positive and negative electrodes, and hence to ensure a higher safety of the battery.