A system for allocating communication IDs comprising: a plurality of slave battery management systems(200_1, 200_2,..., 200_N), BMSs, sequentially connected to a power line (Ls) for supplying power, and allocating predetermined communication IDs based on first current amounts applied through the power line to enter each of the slave BMSs, wherein each of the slave BMSs is configured to consume a current amount (I cc) through the power line for driving and output a second current amount that is the first current amount applied thereto, minus the consumed current amount, and that is the first current amount applied to the slave BMS next in line in the BMS sequence; wherein each slave BMS includes: a shunt resistor (R 1) coupled in series to the power line; a slave storage for storing information for indicating resistance of the shunt resistor and a communication ID allocating table in which a plurality of communication IDs correspond to a plurality of first current amounts are recorded; and a slave controller for measuring voltages at a front end and a rear end of the shunt resistor to calculate a voltage value caused by a voltage drop, calculating the first current amount based on the voltage value and resistance of the shunt resistor, and allocating a communication ID based on the calculated first current amount and the communication ID allocating table, wherein the system further comprises a master BMS including the communication ID allocating table in which a plurality of communication IDs corresponding to a number of the slave BMSs and the first current amounts are recorded into a signal for instructing allocation of the communication IDs and broadcasting the same, the master BMS being configured to receive the calculated first current amounts and the allocated communication ID from the slave BMSs, and compares the received first current amounts and the received communication IDs and the communication ID allocating table to verify allocation of communication IDs of the slave BMSs. a plurality of slave battery management systems(200_1, 200_2,..., 200_N), BMSs, sequentially connected to a power line (Ls) for supplying power, and allocating predetermined communication IDs based on first current amounts applied through the power line to enter each of the slave BMSs, wherein each of the slave BMSs is configured to consume a current amount (I cc) through the power line for driving and output a second current amount that is the first current amount applied thereto, minus the consumed current amount, and that is the first current amount applied to the slave BMS next in line in the BMS sequence; wherein each slave BMS includes: a shunt resistor (R 1) coupled in series to the power line; a slave storage for storing information for indicating resistance of the shunt resistor and a communication ID allocating table in which a plurality of communication IDs correspond to a plurality of first current amounts are recorded; and a slave controller for measuring voltages at a front end and a rear end of the shunt resistor to calculate a voltage value caused by a voltage drop, calculating the first current amount based on the voltage value and resistance of the shunt resistor, and allocating a communication ID based on the calculated first current amount and the communication ID allocating table, wherein the system further comprises a master BMS including the communication ID allocating table in which a plurality of communication IDs corresponding to a number of the slave BMSs and the first current amounts are recorded into a signal for instructing allocation of the communication IDs and broadcasting the same, the master BMS being configured to receive the calculated first current amounts and the allocated communication ID from the slave BMSs, and compares the received first current amounts and the received communication IDs and the communication ID allocating table to verify allocation of communication IDs of the slave BMSs. a shunt resistor (R 1) coupled in series to the power line; a slave storage for storing information for indicating resistance of the shunt resistor and a communication ID allocating table in which a plurality of communication IDs correspond to a plurality of first current amounts are recorded; and a slave controller for measuring voltages at a front end and a rear end of the shunt resistor to calculate a voltage value caused by a voltage drop, calculating the first current amount based on the voltage value and resistance of the shunt resistor, and allocating a communication ID based on the calculated first current amount and the communication ID allocating table, wherein the system further comprises a master BMS including the communication ID allocating table in which a plurality of communication IDs corresponding to a number of the slave BMSs and the first current amounts are recorded into a signal for instructing allocation of the communication IDs and broadcasting the same, the master BMS being configured to receive the calculated first current amounts and the allocated communication ID from the slave BMSs, and compares the received first current amounts and the received communication IDs and the communication ID allocating table to verify allocation of communication IDs of the slave BMSs.