A bus bar holder for connecting electrode terminals of a plurality of batteries arranged in a lengthwise direction, the bus bar holder including a bus bar holder plate having an opening in a lengthwise direction thereof and configured such that at least some electrode terminals of the plurality of batteries are extendable through the opening and slidable along the opening; and a bus bar for electrically connecting at least two electrode terminals of adjacent batteries, wherein the bus bar holder plate includes a settling groove in which the bus bar is settled, and the bus bar attached to the electrode terminals is slidable when the electrode terminal slides along the opening.