The present teaching provides a power supply system capable of fully utilizing a plurality of batteries having different performances. A power supply system disclosed here includes a main line, a plurality of sweep modules, and a controller. Each of the sweep modules includes a battery module and an electric power circuit module. The electric power circuit module includes a switching device for connecting a connection state between the battery modules and the main line between connection and disconnection. The controller performs sweep control of sequentially switching the battery module connected to the main line among the plurality of battery modules. During an input of electric power from outside, the controller disconnects the battery module whose SOC level satisfies a high SOC condition from the main line (S7), and continues sweep control (S8, S9).