A method for charge equalization of a plurality of batteries, the method comprising: calculating first state difference information for each of the plurality of batteries, the first state difference information of each battery indicating a difference between state information of each battery, that is determined based on a physical quantity of the respective battery, and an average state information of the state information, wherein state information includes a state of charge, SOC, and wherein the average state information includes an average of SOC of each battery; calculating second state difference information as a sum of absolute values of the first state difference information of each of the plurality of batteries, the second state difference information indicating a degree of imbalance among the batteries; verifying a range that includes the second state difference information; determining a value corresponding to the verified range as a gain α; and determining a ratio ε n for each of the plurality of batteries between the first state difference information for each of the plurality of batteries and the second state difference information; characterized by determining an average output physical quantity P Average of a plurality of converters, each converter corresponding to each of the batteries, as a ratio of a preset output physical quantity P DCH or I DCH and a number of the converters N; and defining an output value P Target_n for each converter corresponding to each of the plurality of batteries by adding a specific value which is calculated as a product of the gain α, the respective ratio ε n, and the average output physical quantity P Average to the average output physical quantity P Average. calculating first state difference information for each of the plurality of batteries, the first state difference information of each battery indicating a difference between state information of each battery, that is determined based on a physical quantity of the respective battery, and an average state information of the state information, wherein state information includes a state of charge, SOC, and wherein the average state information includes an average of SOC of each battery; calculating second state difference information as a sum of absolute values of the first state difference information of each of the plurality of batteries, the second state difference information indicating a degree of imbalance among the batteries; verifying a range that includes the second state difference information; determining a value corresponding to the verified range as a gain α; and determining a ratio ε n for each of the plurality of batteries between the first state difference information for each of the plurality of batteries and the second state difference information; characterized by determining an average output physical quantity P Average of a plurality of converters, each converter corresponding to each of the batteries, as a ratio of a preset output physical quantity P DCH or I DCH and a number of the converters N; and defining an output value P Target_n for each converter corresponding to each of the plurality of batteries by adding a specific value which is calculated as a product of the gain α, the respective ratio ε n, and the average output physical quantity P Average to the average output physical quantity P Average.