POWER SUPPLY DEVICE

A power supply device (A) includes a terminal (17a, 17b) including an electrode connection part having first and second surfaces directed to opposite sides each other, a first battery cell (2) arranged on one side based on a position of the electrode connection part (17a, 17b), and a second battery cell (2) arranged on the other side based on the position of the electrode connection part (17a, 17b) and stacked on the first battery cell (2). The first battery cell (2) has a first electrode (2b) arranged to be superposed on the first surface of the electrode connection part (17a, 17b). The second battery cell (2) has a second electrode arranged to be superposed on the second surface of the electrode connection part (17a, 17b) .