Bus bar module and battery pack

A bus bar module includes a plurality of bus bars each having a through hole into which an electrode terminal of an electrode terminal group arranged in a line on a battery module formed of a plurality of battery cells is inserted, the bus bars being arranged along an arranging direction of the electrode terminal in the electrode terminal group, and a flat cable including a conductor part electrically connected to the bus bars, and an insulating holding part for holding the bus bars. The bus bar includes a holding body to be fitted to the flat cable. The holding part has a holding hole for each of the bus bars that allows a relative movement of the bus bar with respect to the flat cable in the arranging direction, by allowing a relative movement of the inserted holding body in the arranging direction.