A battery pack comprising: a battery module assembly comprising a plurality of battery cells; a tray assembly having an upper surface on which the battery module assembly is mounted; a cover member having an outer periphery coupled to face an outer periphery, of the tray assembly while the battery module assembly is accommodated therein; and a sealing gasket interposed between the mutually facing outer peripheries (134, 112) of the tray assembly and the cover member, wherein mutually communicating fastening holes are respectively formed in the outer peripheries of the tray assembly, the outer peripheries of the cover member, and the gasket such that first fastening members are inserted thereinto; one or more second fastening members respectively coupled to the first fastening members are positioned under the fastening holes formed on the tray assembly; second fastening members include gasket compression limiters in which one ends thereof pass through the fastening holes of the tray assembly and extend to protrude toward an upper surface of the tray assembly; and the gasket compression limiters are inserted into the fastening holes of the gasket, and the diameters of the outer circumferential surfaces of the gasket compression limiters are relatively greater than the diameters of the outer circumferential surfaces of the first fastening members, wherein the first fastening members and second fastening members are respectively bolts and nuts, and the second fastening members are coupled, by means of a screw structure, to the first fastening members passing through fastening holes respectively formed in the outer peripheries of the cover member, and the gasket, the outer peripheries of the tray assembly, characterized in that the diameters of the gasket compression limiters are formed in sizes of 100% to 110% of the diameters of the outer circumferential surfaces of the first fastening members, wherein the diameters of the outer circumferential surfaces of the first fastening members are the diameters of the bolts head. a battery module assembly comprising a plurality of battery cells; a tray assembly having an upper surface on which the battery module assembly is mounted; a cover member having an outer periphery coupled to face an outer periphery, of the tray assembly while the battery module assembly is accommodated therein; and a sealing gasket interposed between the mutually facing outer peripheries (134, 112) of the tray assembly and the cover member, wherein mutually communicating fastening holes are respectively formed in the outer peripheries of the tray assembly, the outer peripheries of the cover member, and the gasket such that first fastening members are inserted thereinto; one or more second fastening members respectively coupled to the first fastening members are positioned under the fastening holes formed on the tray assembly; second fastening members include gasket compression limiters in which one ends thereof pass through the fastening holes of the tray assembly and extend to protrude toward an upper surface of the tray assembly; and the gasket compression limiters are inserted into the fastening holes of the gasket, and the diameters of the outer circumferential surfaces of the gasket compression limiters are relatively greater than the diameters of the outer circumferential surfaces of the first fastening members, wherein the first fastening members and second fastening members are respectively bolts and nuts, and the second fastening members are coupled, by means of a screw structure, to the first fastening members passing through fastening holes respectively formed in the outer peripheries of the cover member, and the gasket, the outer peripheries of the tray assembly, characterized in that the diameters of the gasket compression limiters are formed in sizes of 100% to 110% of the diameters of the outer circumferential surfaces of the first fastening members, wherein the diameters of the outer circumferential surfaces of the first fastening members are the diameters of the bolts head.