An apparatus for assigning identification information to a plurality of slave battery management units electrically connected one-to-one to a plurality of battery modules mounted on a base plate of a battery pack, wherein each of the slave battery management units activates its antenna by using an operating power, the apparatus comprising: a casing jig configured to at least partially cover the plurality of slave battery management units together with the base plate; a wireless communication unit including a plurality of antennas disposed in a region of the casing jig facing the base plate so as to correspond one-to-one to the plurality of slave battery management units; a power supply unit configured to selectively supply the operating power to at least one of the plurality of slave battery management units; and a controller electrically connected to the wireless communication unit and the power supply unit, wherein the controller is configured to select at least one of the plurality of antennas; transmit, to the wireless communication unit, a first control signal including identification information related to the at least one selected antenna; transmit, to the power supply unit, a second control signal related to the first control signal when transmitting the first control signal, and the wireless communication unit is configured to output a wireless signal indicating the identification information through an antenna associated with the identification information in response to the first control signal, the power supply unit is further configured to supply the operating power to the slave battery management unit corresponding to at least one selected antenna among the plurality of slave battery management units, in response to the second control signal. a casing jig configured to at least partially cover the plurality of slave battery management units together with the base plate; a wireless communication unit including a plurality of antennas disposed in a region of the casing jig facing the base plate so as to correspond one-to-one to the plurality of slave battery management units; a power supply unit configured to selectively supply the operating power to at least one of the plurality of slave battery management units; and a controller electrically connected to the wireless communication unit and the power supply unit, wherein the controller is configured to select at least one of the plurality of antennas; transmit, to the wireless communication unit, a first control signal including identification information related to the at least one selected antenna; transmit, to the power supply unit, a second control signal related to the first control signal when transmitting the first control signal, and the wireless communication unit is configured to output a wireless signal indicating the identification information through an antenna associated with the identification information in response to the first control signal, the power supply unit is further configured to supply the operating power to the slave battery management unit corresponding to at least one selected antenna among the plurality of slave battery management units, in response to the second control signal.