A battery module comprising: a battery stack including a plurality of batteries that are stacked, the plurality of batteries including valves through which a gas is blown off and being prismatic; a duct plate configured to cover a surface of the battery stack on which the valves are disposed, the duct plate including a gas discharge duct that extends in a stacking direction (X) of the batteries , is connected to the valves of the batteries , and temporarily stores the gas blown off through the valves; a cover plate placed on the duct plate ; and a flow path defined by the duct plate and the cover plate , the flow path extending from the gas discharge duct in a first direction that intersects with the stacking direction of the batteries and allowing leaking of the gas in the gas discharge duct to an outside of the battery module , the first direction being an horizontal direction (Y), the battery module further comprising flow path outlets connected to the flow path and disposed at end portions of the battery module in the horizontal direction (Y), wherein the cover plate includes a plurality of openings that are formed in the cover plate on both side of the cover plate in the horizontal direction (Y) at a predetermined interval in the stacking direction (X) in a state where gas discharge duct is sandwiched between the plurality of openings , the openings through which a midst part of the flow path is communicable with the outside of the battery module , wherein a first end of the respective openings in a vertical direction (Z) being connected to regions each between an opening of the flow path and the flow path outlets , a second end of the respective opening in the vertical direction (Z) being connected to the outside of the battery module , wherein a size of the opening is set in a state where a flow path resistance in the opening is larger than a flow path resistance of the flow path . a battery stack including a plurality of batteries that are stacked, the plurality of batteries including valves through which a gas is blown off and being prismatic; a duct plate configured to cover a surface of the battery stack on which the valves are disposed, the duct plate including a gas discharge duct that extends in a stacking direction (X) of the batteries , is connected to the valves of the batteries , and temporarily stores the gas blown off through the valves; a cover plate placed on the duct plate ; and a flow path defined by the duct plate and the cover plate , the flow path extending from the gas discharge duct in a first direction that intersects with the stacking direction of the batteries and allowing leaking of the gas in the gas discharge duct to an outside of the battery module , the first direction being an horizontal direction (Y), the battery module further comprising flow path outlets connected to the flow path and disposed at end portions of the battery module in the horizontal direction (Y), wherein the cover plate includes a plurality of openings that are formed in the cover plate on both side of the cover plate in the horizontal direction (Y) at a predetermined interval in the stacking direction (X) in a state where gas discharge duct is sandwiched between the plurality of openings , the openings through which a midst part of the flow path is communicable with the outside of the battery module , wherein a first end of the respective openings in a vertical direction (Z) being connected to regions each between an opening of the flow path and the flow path outlets , a second end of the respective opening in the vertical direction (Z) being connected to the outside of the battery module , wherein a size of the opening is set in a state where a flow path resistance in the opening is larger than a flow path resistance of the flow path . <EOS>