To provide a battery module capable of perfectly preventing the intrusion of water, suppressing the expansion of an armoring material caused by an internal pressure rise of electric cells comprising lithium batteries, and improving battery life characteristics such as the degradation and the output drop of the battery.

This battery module is provided with: the lithium batteries each composed by sealing a battery body with the armoring material by projecting metal terminals to the outside; a battery group composed by electrically connecting the plurality of lithium batteries to one another through the metal terminals; and a sealable armoring casing housing the battery group and having external terminals, and is so structured that the battery group is housed in the armoring casing, and the armoring casing is sealed by connecting the metal terminals without being electrically connected of the battery group to the external terminals through lead wires. In the battery module, the armoring casing is kept in a positive pressure state higher than that of the atmospheric pressure.