BATTERY PACK

PROBLEM TO BE SOLVED: To provide a battery pack which has a function to restrain each battery cell and can improve the cooling performance of the battery cell by suppressing flow resistance.SOLUTION: A battery pack 1 comprises a plurality of plate-like projections 23, 24, and 25 arranged side by side at intervals on side faces 2a and 2b of battery cells 2 opposing each other in a stacking direction X. The plurality of plate-like projections 23, 24, and 25 are in contact with exterior cases of the opposing battery cells 2 and form fluid passages 10 between side faces of the battery cells. The plurality of plate-like projections 23, 24, and 25 are arranged side by side on the side faces 2a and 2b of the battery cells at predetermined intervals in a flow direction F of a cooling fluid and in a direction Y orthogonal to the flow direction F. Further, the plate-like projections 23, 24, and 25, which are positioned in a plurality of columns in the orthogonal direction Y, are arranged such that columns adjacent in the orthogonal direction Y are displaced from each other in the flow direction F.