A battery pack includes a case having an inner space, a plurality of battery cells placed inside the case, and at least one spacer placed between the battery cells. A space is formed around a supporting portion of the spacer for the battery cells so as to allow heat generated by the battery cells to flow out of the case. The spacer supports the battery cells by line contact therewith. The spacer body is formed in the shape of an H beam or in the shape of a staircase.