A battery module includes a plurality of battery cells, a holder, and a bus-bar. The plurality of battery cells are arranged along one direction, and each of the plurality of battery cells includes a terminal and a vent at an upper surface. The holder is on the plurality of battery cells and has an opening through which the terminal is exposed. The bus-bar is has a portion in the opening of the holder and electrically couples adjacent ones of the plurality of battery cells. The holder includes a bus-bar fastening portion at an area corresponding to the terminal and an exhaust portion at an area corresponding to the vent. The bus-bar fastening portion and the exhaust portion are integrally formed.