A battery pack includes a pack tray; and at least one battery module provided on the pack tray. The at least one battery module includes a battery cell assembly mounted on the pack tray and including at least one battery cell; a pair of side plates provided on both side surfaces of the battery cell assembly to support the battery cell assembly and fixed to the pack tray; and a band unit connected to the pair of side plates and configured to at least partially cover an upper side and a lower side of the battery cell assembly.