BATTERY PACK

A partial structure of a battery pack includes: a battery group which is formed by stacking a plurality of layers, each of the layers being formed by arranging cylindrical batteries in parallel in a plane, the cylindrical batteries belonging to adjacent layers being arranged by shifting alignment pitches by a half pitch from each other between the adjacent layers; heat transfer plates, wherein each of the heat transfer plates is in contact with side surfaces of the cylindrical batteries arranged on both surfaces of each of the heat transfer plates, is formed by a heat transfer corrugated plate member, and extends through a gap between the cylindrical batteries along an alignment direction of the cylindrical batteries in the layers in the plane intersecting center axis lines of the cylindrical batteries, a first intersection direction intersecting the alignment direction or a second intersection direction intersecting the alignment direction and the first intersection direction; and a radiator which is arranged on a side of the battery group and is connected with a edge of each of the heat transfer plates, wherein each of the cylindrical batteries is contact with at least two of the heat transfer plates.