A module of the present invention is formed by housing, in a housing container, a cell stack device that includes cell stacks comprising an arrangement of a plurality of cells. The housing container includes a housing chamber that houses the cell stack device; a first gas introduction section provided in a lower portion of the housing chamber and configured to introduce a first gas supplied into the housing chamber; and a first gas circulation section provided on a side of the housing chamber and connected to the first gas introduction section. The width of the first gas circulation section is narrower than the width of the first gas introduction section.