A battery management system that estimates an internal impedance of a battery, a method of driving the same, a device that estimates an internal impedance of a battery, and a method of estimating the internal impedance of a battery. A method of driving a battery management system that estimates the internal impedance of a battery including a plurality of cells includes generating a battery equivalent model of the battery, receiving a terminal voltage signal and a charge and discharge current signal of the battery, and generating a first discrete signal corresponding to the terminal voltage signal of the battery and a second discrete signal corresponding to the charge and discharge current signal of the battery, and filtering the first discrete signal and the second discrete signal according to a frequency range corresponding to the battery equivalent model so as to estimate the internal impedance of the battery. The device that estimates an internal impedance of a battery filters the first discrete signal and the second discrete signal according to a frequency range corresponding to the battery equivalent model so as to estimate the internal impedance of the battery.