Abstract: A manifold includes: a valve configured to control a flow of fluid; and a housing having, in an internal space, a plurality of flow path chambers which is partitioned by a partition wall and through which the fluid flows. The housing includes a joining portion where an upper housing having a first opening opened downward and a lower housing having a second opening opened upward are joined by thermally welding the first opening and the second opening, and the joining portion is disposed above or below a center of the housing in an upper-lower direction.