The present disclosure provides a battery pack including a battery cell array in which a plurality of battery cells are arranged in a state in which side surfaces thereof face each other, a heater disposed between the battery cells, a battery management system (BMS) configured to control an operation of the battery cells, and a temperature sensor configured to measure a temperature of the battery cells to transmit the measured temperature to the BMS. Here, when the temperature of the battery cells, which is measured from the temperature sensor, is equal to or less than a critical temperature, the BMS provides a current to the heater to increase the temperature of the battery cells.