BATTERY PACK WITH IMPROVED SAFETY

A battery pack includes: a cell module assembly including a battery cell stack in which a plurality of battery cells are stacked; an electrical connection unit including a connector for an electrical connection between the battery pack and another battery pack when a plurality of battery packs are stacked; a pack case that houses the cell module assembly and the electrical connection unit in an inside of the pack case, the pack case being opened at an upper surface; and a fire extinguishing tank that covers an upper part of the pack case, wherein the pack case includes a first connector through-hole portion in a shape of an opening on a lower surface of the pack case so that the connector is electrically connected to the battery pack stacked on a lower part of the plurality of battery packs.