An apparatus for estimating a resistance of a battery based on an operation state of the battery corresponding to a resistance correcting condition, the apparatus for estimating a resistance of a battery comprising: a sensing unit configured to measure voltage, current and temperature of a battery; and a processor operably coupled to the sensing unit, wherein the processor is configured to: calculate a measured resistance of the battery by using the voltage and the current of the battery, determine that the operation state of the battery corresponds to the resistance correcting condition, wherein the operation state of the battery is a state of charge "SOC of the battery and the temperature of the battery, wherein the operation state of the battery corresponds to the resistance correcting condition when at least one of a condition in which the SOC of the battery is included in a preset SOC range and a condition in which the temperature of the battery is included in a preset temperature range is satisfied, calculate a measured charge/discharge rate of the battery by using the voltage and the current of the battery, calculate an increase/decrease rate of a beginning of life "BOL" resistance according to the measured charge/discharge rate relative to the BOL resistance according to a preset reference charge/discharge rate as the resistance increase/decrease rate, correct the measured resistance by using the calculated resistance increase/decrease rate of the BOL resistance of the battery according to the calculated charge/discharge rate when the operation state of the battery corresponds to the resistance correcting condition, and determine the corrected measured resistance as a resistance of the battery. a sensing unit configured to measure voltage, current and temperature of a battery; and a processor operably coupled to the sensing unit, wherein the processor is configured to: calculate a measured resistance of the battery by using the voltage and the current of the battery, determine that the operation state of the battery corresponds to the resistance correcting condition, wherein the operation state of the battery is a state of charge "SOC of the battery and the temperature of the battery, wherein the operation state of the battery corresponds to the resistance correcting condition when at least one of a condition in which the SOC of the battery is included in a preset SOC range and a condition in which the temperature of the battery is included in a preset temperature range is satisfied, calculate a measured charge/discharge rate of the battery by using the voltage and the current of the battery, calculate an increase/decrease rate of a beginning of life "BOL" resistance according to the measured charge/discharge rate relative to the BOL resistance according to a preset reference charge/discharge rate as the resistance increase/decrease rate, correct the measured resistance by using the calculated resistance increase/decrease rate of the BOL resistance of the battery according to the calculated charge/discharge rate when the operation state of the battery corresponds to the resistance correcting condition, and determine the corrected measured resistance as a resistance of the battery. calculate a measured resistance of the battery by using the voltage and the current of the battery, determine that the operation state of the battery corresponds to the resistance correcting condition, wherein the operation state of the battery is a state of charge "SOC of the battery and the temperature of the battery, wherein the operation state of the battery corresponds to the resistance correcting condition when at least one of a condition in which the SOC of the battery is included in a preset SOC range and a condition in which the temperature of the battery is included in a preset temperature range is satisfied, calculate a measured charge/discharge rate of the battery by using the voltage and the current of the battery, calculate an increase/decrease rate of a beginning of life "BOL" resistance according to the measured charge/discharge rate relative to the BOL resistance according to a preset reference charge/discharge rate as the resistance increase/decrease rate, correct the measured resistance by using the calculated resistance increase/decrease rate of the BOL resistance of the battery according to the calculated charge/discharge rate when the operation state of the battery corresponds to the resistance correcting condition, and determine the corrected measured resistance as a resistance of the battery.