Provided are battery packs capable of preventing electrical shorts due to incorrect arrangement of polarities of the battery packs during assembly of an uninterruptible power supply (UPS) having the battery packs and a UPS having the battery packs. The battery pack includes: a casing housing a plurality of cells; first and second terminals arranged to protrude outwardly from a first surface of the casing and having opposite polarities; a first attachment unit formed on a second surface of the casing; and a second attachment unit formed on a third surface of the casing, disposed opposite the second surface of the casing, wherein the first attachment unit and the second attachment unit are not symmetrical to each other.