A battery module, including: a plurality of battery cells, and a barrier (120, 220) comprising a barrier main body (125, 225), wherein each of the battery cells comprises a cap plate and at least one side surface, wherein at least two battery cells are positioned side by side as a first group of battery cells facing one side of the barrier main body (125, 225) and at least two battery cells are positioned side by side as a second group of battery cells facing the opposite side of the barrier main body (125, 225), the barrier (120, 220) comprises a partition wall (121, 221) provided on at least one side of the barrier main body (125, 225), wherein the partition wall (121, 221) is positioned between the battery cells of the respective first and/or second group of battery cells, characterised in that the barrier (120, 220) comprises flange portions (122a, 122b, 123a, 123b) formed to surround the outline of the barrier main body (125, 225) and the respective group of battery cells together with the partition wall (121, 221), wherein the cap plates are positioned on opposite sides of the respective group of battery cells, and the flange portions (122a, 122b, 123a, 123b) include first and second flange portions (122a, 122b) covering the respective cap plates of the battery cells, or wherein the cap plates are positioned on the same side of the respective group of battery cells, and the flange portions (122a, 122b, 123a, 123b) include a first flange portion covering the cap plates of the battery cells of the respective group of battery cells, and a second flange portion positioned to face the first flange portion, and wherein the flange portions (122a, 122b, 123a, 123b) further include third and fourth flange portions (123a, 123b) provided between the first and second flange portions (122a, 122b) so as to cover one side surface of at least one battery cell of the respective group of battery cells. a plurality of battery cells, and a barrier (120, 220) comprising a barrier main body (125, 225), wherein each of the battery cells comprises a cap plate and at least one side surface, wherein at least two battery cells are positioned side by side as a first group of battery cells facing one side of the barrier main body (125, 225) and at least two battery cells are positioned side by side as a second group of battery cells facing the opposite side of the barrier main body (125, 225), the barrier (120, 220) comprises a partition wall (121, 221) provided on at least one side of the barrier main body (125, 225), wherein the partition wall (121, 221) is positioned between the battery cells of the respective first and/or second group of battery cells, characterised in that the barrier (120, 220) comprises flange portions (122a, 122b, 123a, 123b) formed to surround the outline of the barrier main body (125, 225) and the respective group of battery cells together with the partition wall (121, 221), wherein the cap plates are positioned on opposite sides of the respective group of battery cells, and the flange portions (122a, 122b, 123a, 123b) include first and second flange portions (122a, 122b) covering the respective cap plates of the battery cells, or wherein the cap plates are positioned on the same side of the respective group of battery cells, and the flange portions (122a, 122b, 123a, 123b) include a first flange portion covering the cap plates of the battery cells of the respective group of battery cells, and a second flange portion positioned to face the first flange portion, and wherein the flange portions (122a, 122b, 123a, 123b) further include third and fourth flange portions (123a, 123b) provided between the first and second flange portions (122a, 122b) so as to cover one side surface of at least one battery cell of the respective group of battery cells.