A battery cell module includes a plurality of battery cells arranged to each other, bus bars used to connect external terminals of the plurality of battery cells, and separators provided between adjacent battery cells. Each battery cell includes an electrode body, a casing that houses the electrode body, and external terminals, provided external to the casing, which are electrically connected to the electrode body. The separator includes a heat transfer section that performs heat transfer between the heat section and the battery cell and an insulator that electrically insulates between the heat transfer section and the battery cell. The heat transfer section has a thermal conductivity higher than that of the insulator.