Battery Pack

Provided is a battery pack including a battery module including one or more battery cells; an accommodating body accommodating the battery module; an accommodating cover coupled to the accommodating body to form, together with the accommodating body, a module accommodating space in which the battery module is accommodated; a fire extinguishing portion provided in the accommodating cover and supplying a fire extinguishing agent accommodated therein to the module accommodating space when the temperature of the module accommodating space is equal to or higher than a preset first temperature; and a variable portion which is located between the battery module and the fire extinguishing portion and of which shape or length is changed to expose the fire extinguishing portion toward the battery module when the temperature of the module accommodating space reaches a preset second temperature which is lower than the first temperature.