CELL MODULE

A battery module (100) includes: a plurality of cells (10) connected in parallel; and a holder (20) configured to house the cells (10). In each of the cells (10), an electrode group (4) including a positive electrode (1), a negative electrode (2), and a separator (3) is housed in a cell case (7). The cell case (7) is electrically connected to one of the positive electrode (1) or the negative electrode (2) to have a first electric potential. The holder (20) includes a plurality of housings (21) each housing an associated one of the cells (10), and has a second electric potential opposite to the first electric potential. The cells (10) are housed in the housings (21) with the cell cases (7) being insulated from the holder (20).