POWER SUPPLY DEVICE, ELECTRIC VEHICLE PROVIDED WITH POWER SUPPLY DEVICE, AND POWER STORAGE DEVICE

A power supply device connects a plurality of battery modules (10) including a plurality of battery cells (1) by power line (42). Battery module (10) includes cell monitor circuit (6) that detects battery information, and a plurality of cell monitor circuits (6) provided in each battery module (10) are cascade-connected via communication line (44). Cell monitor circuit (6) includes communication interface (48) including connection parts (43) formed by connecting communication line (44), and communication interface (48) sets a withstand voltage applied to connection part (43) to be higher than an output voltage of the power supply device.