Abstract: The present invention relates to a side frame for a battery case, which can achieve lightweight and cost reduction simultaneously while sufficiently protecting battery cells against the external shock, and the side frame for a battery case according to an embodiment comprises: a first frame unit formed to have an open end surface; and a second frame unit which is arranged in the first frame unit to close the open end surface of the first frame unit and is coupled to the first frame unit, wherein the first frame unit and the second frame unit may be formed of different materials from each other.