A battery module includes a plurality of battery cells connected in series. Each of the battery cells has a rectangular thin plate shape, and includes a thin plate-shaped positive electrode tab and a thin plate-shaped negative electrode tab, which are provided on one side of the battery cell. Among the battery cells, the side of one battery cell where the positive electrode tab and the negative electrode tab are provided and the side of another battery cell where the positive electrode tab and the negative electrode tab are provided, are arranged so as to face each other. The positive electrode tab of the one battery cell and the negative electrode tab of the other battery cell are overlapped with each other in a thickness direction of the battery cells and in contact with each other.