Disclosed is a battery management system, the battery management system including: a module control unit (MCU) which includes a communication module, a capacitor which is connected to the communication module, and a charging module which is connected to the capacitor to charge the capacitor; and a battery control unit (BCU) which transmits a square wave clock signal which enables a communication module of the MCU and controls the MCU, in which when the capacitor is charged with a voltage which is equal to or higher than a predetermined reference voltage, the MCU turns on the communication module.