A battery module includes: a plurality of battery cells stacked in a horizontal direction; a first plate supporting lower sides of the plurality of the battery cells and dissipating heat generated in the battery cells; and a second plate in contact with upper sides of the battery cells and dissipating heat generated in the battery cells, wherein the second plate comprises accommodation grooves to receive corresponding sealing portions formed in the upper sides of the battery cells, wherein a heat transfer material having a dielectric strength of from 10 kV/mm to 30 kV/mm is disposed in the accommodation grooves.