A power supply system including a plurality of batteries includes a busbar, a terminal and a busbar module. The busbar connects a first electrode of one of the batteries with a second electrode of another one of the batteries. The terminal is mounted on the busbar and is contacted with the first electrode. The busbar module has a bulkhead defining a space accommodating the busbar. A locking member is extended from the bulkhead into the space and restricts the busbar. An abutment portion is provided at an edge part of the terminal. The abutment portion abuts the locking member when the terminal is rotated about the first electrode.