POWER SUPPLY DEVICE, AND ELECTRIC VEHICLE AND POWER STORAGE DEVICE EQUIPPED WITH THIS POWER SUPPLY DEVICE

A power supply device includes battery stack (2) in which a plurality of battery cells (1) are stacked, and a plurality of battery modules (10) including cell monitor circuits (6) that detect battery information of battery cells (1), and cell monitor circuits (6) of the battery modules (10) are cascade-connected via communication lines (44). Battery module (10) includes a pair of communication terminals (43) that are arranged at both ends and are connected to cell monitor circuit (6), and inner wires (45) that connect the pair of communication terminals (43) positioned at both the ends. Communication line (44) is connected to communication terminal (43), and cell monitor circuits (6) of the plurality of battery modules (10) are cascade-connected.