A battery comprises: a plurality of cells each of which has two electrodes; a control unit with a circuit board; and a housing that contains the cells and the control unit. The housing is provided with a first terminal and a second terminal. The cell, which is disposed closest to the first terminal, is connected to the first terminal; and the cell, which is disposed adjacent to the control unit, is connected to the second terminal via the control unit. Among the cells and the control unit, the control unit is disposed closest to the second terminal. A bus bar is provided between the cell and the cell so as to serve as a folding portion that folds back the current path between the first and second terminals.