POWER SUPPLY DEVICE

Uneven distribution of current is suppressed even in a condition that semiconductor elements are mounted in a limited area on a circuit board. A power supply device includes a secondary battery cell, charging/discharging FETs (21-28), and a circuit board (30) including a first terminal block (31) and a second terminal block (32). A first charging/discharging FET (21) and a third charging/discharging FET (23) are disposed at a side of the first terminal block on circuit board (30). A second charging/discharging FET (22) and a fourth charging/discharging FET (24) are disposed at a side of the second terminal block on circuit board (30). A first current path (41) connecting the first charging/discharging FET (21) in series to the second charging/discharging FET (22) is longer than a second current path (42) connecting the third charging/discharging FET (23) in series to the fourth charging/discharging FET (24). The first current path (41) includes a first current impeding region (51) configured to impede current flow. The second current path (42) includes a second current impeding region (52) configured to impede current flow. A second electrical resistance (52R) of the second current impeding region (52) is higher than a first electrical resistance (51R) of the first current impeding region (51).