A battery pack including: a case accommodating a plurality of unit cells each having a first electrode and a second electrode; and a connector provided in the case, the battery pack comprising: a first core pack and a second core pack each configured to hold a plurality of the unit cells, the first core pack and the second core pack being accommodated in the case so as to face each other, wherein, in the first core pack and the second core pack, first cell groups (40a to 40h) are constituted by a plurality of the unit cells that are positioned in such a manner that the first electrodes thereof are directed in a same direction, and second cell groups (42a to 42f) are constituted by a plurality of the unit cells that are positioned in such a manner that the first electrodes thereof are directed in a direction opposite to the direction in which the first electrodes of the unit cells of the first cell groups are directed, the first cell groups and the second cell groups being arranged alternately; first busbars electrically connect the unit cells of one of the first cell groups and the unit cells of one of the second cell groups in the first core pack or the second core pack; a second busbar electrically connects the unit cells of one of the first cell groups or the second cell groups in the first core pack and the unit cells of one of the first cell groups or the second cell groups in the second core pack; a third busbar electrically connects the connector and the unit cells of one of the first cell groups or the second cell groups that is closest to the connector in the first core pack or the second core pack; and a fourth busbar electrically connects the connector and the unit cells of one of the first cell groups or the second cell groups that is most distant from the connector in the first core pack or the second core pack, wherein the second busbar is provided in singularity, and the single second busbar electrically connects the unit cells of one of the first cell groups or the second cell groups that is closest to the connector in the first core pack, and the unit cells of one of the first cell groups or the second cell groups that is most distant from the connector in the second core pack. a first core pack and a second core pack each configured to hold a plurality of the unit cells, the first core pack and the second core pack being accommodated in the case so as to face each other, wherein, in the first core pack and the second core pack, first cell groups (40a to 40h) are constituted by a plurality of the unit cells that are positioned in such a manner that the first electrodes thereof are directed in a same direction, and second cell groups (42a to 42f) are constituted by a plurality of the unit cells that are positioned in such a manner that the first electrodes thereof are directed in a direction opposite to the direction in which the first electrodes of the unit cells of the first cell groups are directed, the first cell groups and the second cell groups being arranged alternately; first busbars electrically connect the unit cells of one of the first cell groups and the unit cells of one of the second cell groups in the first core pack or the second core pack; a second busbar electrically connects the unit cells of one of the first cell groups or the second cell groups in the first core pack and the unit cells of one of the first cell groups or the second cell groups in the second core pack; a third busbar electrically connects the connector and the unit cells of one of the first cell groups or the second cell groups that is closest to the connector in the first core pack or the second core pack; and a fourth busbar electrically connects the connector and the unit cells of one of the first cell groups or the second cell groups that is most distant from the connector in the first core pack or the second core pack, wherein the second busbar is provided in singularity, and the single second busbar electrically connects the unit cells of one of the first cell groups or the second cell groups that is closest to the connector in the first core pack, and the unit cells of one of the first cell groups or the second cell groups that is most distant from the connector in the second core pack.