A battery pack raises an alarm under overheated or high pressure conditions in the battery pack. The alarm is raised from the battery pack or an external device that is coupled with the battery pack when the temperature or the pressure of the battery pack exceeds a predetermined level. The battery pack includes a terminal that is coupled with a charging device or an external device, a battery cell coupled with the terminal so that the battery cell can be charged or discharged, a sensor that is installed in the battery cell to detect at least one of a temperature and a pressure of the battery cell, and an alarm unit that compares a value detected by the sensor with a reference level and raises an alarm for a user when the value detected by the sensor exceeds the reference level.