BATTERY PACK

A battery pack capable of suppressing heat generation from current flowing through a bus bar and suppressing cell deterioration includes first to fourth stacked cells, each cell including positive electrode terminal and a negative electrode terminal having higher conductivity, and a bus bar electrically connecting the positive electrode terminal of the second cell and the negative electrode terminal of the third cell, the second and third cells being disposed side-by-side. The bus bar includes a first conductive part connected to the positive electrode terminal of the second cell, a second conductive part connected to the negative electrode terminal of the third cell and having higher conductivity and higher specific gravity, and a connecting part that connects the first conductive part and the second conductive part. The connecting part is disposed in a first region facing the second cell or in a second region facing the third cell.