A battery pack includes a plurality of unit cells, a substrate electrically connected to the unit cells, a temperature protection device on the substrate, and a protection circuit module electrically connected to the substrate. The temperature protection device includes at least one metal contact electrically connected to the substrate. The substrate includes at least one hole at a location corresponding to the at least one metal contact. A width of the substrate is substantially equal to or less than widths of surfaces of the unit cells overlapping the substrate.