A battery pack and a controlling method thereof are disclosed. In one aspect, the battery pack includes a charge/discharge control switch connected between the battery cell and a terminal of the battery pack and configured to control charge and discharge current of the battery cell. The battery pack also includes a battery management system configured to generate an operating signal to control the charge/discharge control switch, wherein the operating signal comprises a first operating signal having a varying level or a second operating signal having a constant level. The battery pack further includes a monitoring unit configured to control an on/off state of the charge/discharge control switch based at least in part the operating signal received from the battery management system, and a blocking unit configured to turn off the charge/discharge control switch based at least in part a blocking signal received from the battery management system.