Disclosed is a non-aqueous electrolyte battery comprising: a flat outer jacket comprising a metal sheet and having two primary flat portions facing each other; two active material layers of a first polarity respectively carried on inner surfaces of the flat portions; an electrode plate of a second polarity disposed in a position facing with each of the active material layers; and a separator layer interposed between each of the active material layers and the electrode plate of a second polarity, with the outer jacket serving as a current collector of the active material layers.