BATTERY PACK

At least one of a first bus bar module (30A) and a second bus bar module (30B) has a positioning mechanism (330A, 330B) that is inserted between a first stack (10A) and a second stack (10B) and that positions the first bus bar module (30A) or the second bus bar module (30B) in a direction (second direction) orthogonal to a stacking direction (first direction) of battery cells.