To provide a secondary battery pack system that controls battery packs which are connected in parallel without requiring a complex system configuration, a secondary battery pack system of the present invention that supplies power to an electronic device includes a plurality of battery packs each having a controller, a main body side connection circuit which is provided on the electronic device side so as to be connected to the plurality of battery packs, and a main body side discharge control signal line which is provided in the main body side connection circuit. The main body side discharge control signal line and controllers of the plurality of battery packs are connected to each other.