Provided is a battery module including a flexible member including: a housing; at least one separation wall partitioning an inside of the housing into a predetermined number of separated spaces; at least two unit battery cells including a case, a battery cell included in the case, and negative and positive electrodes tabs connected to the battery cell; and a flexible member inserted between the unit battery cells, wherein the unit battery cells and the flexible member are included in a space partitioned by the separation wall.