A battery module provided in a vehicle, includes a holder plate. The holder plate includes openings, a first end surface, a second end surface, support portions and a vulnerable portion. The openings are configured such that cells are inserted in the openings respectively. The first end surface is configured to receive a collision load of a collision object to collide from a third direction. The second end surface is placed on an opposite side to the first end surface in the third direction of the holder plate. The holder plate is supported by the support portions so as to define a space between the second end surface and an adjacent member in the third direction. The vulnerable portion is configured to break the holder plate along a boundary between a first battery group and a second battery group when the vulnerable portion receives the collision load.