It is an object to quickly disperse heat generated when short circuit occurs between a positive electrode and a negative electrode. A nonaqueous-electrolyte battery is disclosed which incorporates: an encapsulating medium constituted by a laminated film in which a unit cell is accommodated, wherein the laminated film of the encapsulating medium contains a metal material having a heat conductivity k at room temperatures which is 230 Wm−1K−1 or higher. Moreover, ratio R of the volume of the metal material portion of the encapsulating medium with respect to a capacity of 1 mAh of the unit cell is 0.0002 cm3/mAh≦R≦0.003 cm3/mAh.