A film package battery 1 has a battery element (20) having a positive electrode, a negative electrode and a separator that are stacked or wound, wherein, at least at 200° C., the separator does not melt or soften and has a heat shrinkage ratio of 3% or less; a film package (10) enclosing the battery element; and a fixing tape (70) fixed to a part of the battery element and fixed to an inner surface of the film package.