Disclosed herein is a battery pack, temperature of which is controllable, including at least one battery module including a plurality of battery cells or unit modules (‘unit cells’) which can be charged and discharged, a fluid channel formed such that a fluid to cool or heat the battery module passes through the battery module, a flow change unit located on the fluid channel to change a flow direction of the fluid based on a temperature state of the battery module, and an operation controller to control an operation of the flow change unit based on information regarding the temperature of the battery module.