PROBLEM TO BE SOLVED: To provide a battery unit capable of improving assemblability thereof.SOLUTION: A battery unit 1 includes: a battery module group 10 in which a plurality of battery modules 11 including a plurality of electric cells housed therein are stacked; a water jacket 20 provided in a direction orthogonal to the lamination direction of the battery modules 11 and heating or cooling the battery module group 10 with a heating/cooling medium supplied to the inside thereof; and a heat conducting gel 30 interposed between the battery module group 10 and the water jacket 20. The battery module group 10 has an escape part 13 with a recessed shape on the side of the water jacket 20.
