A battery pack includes first and second battery modules arranged in a first direction. In the first battery module, a first heat transfer part and a first heat insulator are disposed between battery cells adjacent in a second direction orthogonal to the first direction. In the second battery module, a second heat transfer part and a second heat insulator are disposed between battery cells adjacent in the second direction. The first heat transfer part constitutes a part of a heat transfer component that is put across and connected to both the first and the second battery modules. The first heat transfer part is connected to one of the battery cells in the first battery module so as to enable heat transfer. The second heat transfer part constitutes another part of the heat transfer component and is connected to one of the battery cells in the second battery module.