Battery pack having structure capable of swelling control and vehicle including the battery pack

A battery pack includes a plurality of battery modules; a pack tray in which the plurality of battery modules are accommodated; a module cover covering an opening portion formed over the pack tray; a pack cover covering the module cover; and an upper elastic member located between the module cover and the pack cover and compressed, when the module cover moves toward the pack cover due to swelling of the battery module, to absorb volume expansion due to the swelling.