A battery module, comprising: a battery cell assembly having a plurality of battery cells stacked on each other; a pair of end plates provided at both sides of the battery cell assembly; and a cover frame coupled to the pair of end plates to cover the battery cell assembly, the cover frame being deformed along an inflating direction of the plurality of battery cells when the plurality of battery cells are inflated, wherein the inflating direction of the plurality of battery cells is a direction toward both sides of the battery cell assembly, wherein the cover frame has an elastic deforming portion that is elastically deformed in the direction toward both sides of the battery cell assembly when the plurality of battery cells are inflated, wherein the elastic deforming portion has a groove shape with a predetermined size and is provided in plural such that the plurality of elastic deforming portions are spaced apart from each other by a predetermined distance along a longitudinal direction of the battery cell assembly, and wherein the plurality of elastic deforming portions include: a center groove formed at a center of the cover frame to be formed convex along a front and rear direction of the cover frame; a front edge groove spaced apart from the center groove and provided at a front edge of the cover frame; a plurality of front grooves disposed between the front edge groove and the center groove, spaced apart from each other by a predetermined distance along the front and rear direction of the cover frame, and formed convex toward a front side of the cover frame; a plurality of rear grooves disposed to face the plurality of front grooves with the center groove being interposed therebetween, the plurality of rear grooves being formed convex toward a rear side of the cover frame; and a rear edge groove spaced apart from the plurality of rear grooves and provided at a rear edge of the cover frame. a battery cell assembly having a plurality of battery cells stacked on each other; a pair of end plates provided at both sides of the battery cell assembly; and a cover frame coupled to the pair of end plates to cover the battery cell assembly, the cover frame being deformed along an inflating direction of the plurality of battery cells when the plurality of battery cells are inflated, wherein the inflating direction of the plurality of battery cells is a direction toward both sides of the battery cell assembly, wherein the cover frame has an elastic deforming portion that is elastically deformed in the direction toward both sides of the battery cell assembly when the plurality of battery cells are inflated, wherein the elastic deforming portion has a groove shape with a predetermined size and is provided in plural such that the plurality of elastic deforming portions are spaced apart from each other by a predetermined distance along a longitudinal direction of the battery cell assembly, and wherein the plurality of elastic deforming portions include: a center groove formed at a center of the cover frame to be formed convex along a front and rear direction of the cover frame; a front edge groove spaced apart from the center groove and provided at a front edge of the cover frame; a plurality of front grooves disposed between the front edge groove and the center groove, spaced apart from each other by a predetermined distance along the front and rear direction of the cover frame, and formed convex toward a front side of the cover frame; a plurality of rear grooves disposed to face the plurality of front grooves with the center groove being interposed therebetween, the plurality of rear grooves being formed convex toward a rear side of the cover frame; and a rear edge groove spaced apart from the plurality of rear grooves and provided at a rear edge of the cover frame. a center groove formed at a center of the cover frame to be formed convex along a front and rear direction of the cover frame; a front edge groove spaced apart from the center groove and provided at a front edge of the cover frame; a plurality of front grooves disposed between the front edge groove and the center groove, spaced apart from each other by a predetermined distance along the front and rear direction of the cover frame, and formed convex toward a front side of the cover frame; a plurality of rear grooves disposed to face the plurality of front grooves with the center groove being interposed therebetween, the plurality of rear grooves being formed convex toward a rear side of the cover frame; and a rear edge groove spaced apart from the plurality of rear grooves and provided at a rear edge of the cover frame.