A multi-series battery control system comprises battery cell groups each having a plurality of serially connected battery cells, a plurality of integrated circuits each disposed in correspondence to one of the battery cell groups and a battery control device that exchanges signals with the individual integrated circuits. Each integrated circuit includes an address setting means that receives a message unique to the integrated circuit, different from messages sent to other integrated circuits, from the battery control device, writes over an initialized address of the integrated circuit with the message and alters the message to a message with which an initialized address of another integrated circuit cannot be overwritten in a step assigned with an ordinal number matching the position of the integrated circuit with regard to the connection order.