A rechargeable battery module including: a plurality of unit cells arranged along a first direction and electrically coupled to each other via a bus bar; an end support configured to respectively support an outermost one of the unit cells along the first direction, the end support including an electrically insulative material; an end plate coupled to an edge of the end support, at least one of the end support and the end plate including an absorbing portion configured to absorb swelling of the unit cells in the first direction; and a plurality of side plates at opposite ends of the unit cells in a second direction crossing the first KWK