Apparatus and method for estimating internal resistance of battery

Provided are an apparatus and a method for estimating internal resistance of a battery pack. The apparatus includes: a voltage sensing unit that measures a voltage value of the battery pack; a current sensing unit that measures a current value of the battery pack; a temperature sensing unit that measures a temperature value of the battery pack; and a microprocessor unit (MCU) that calculates the internal resistance of the battery pack using values transferred from the voltage sensing unit, the current sensing unit, and the temperature sensing unit.