A valve includes a housing and a valve diaphragm. The housing includes a first housing member and a second housing member. The first housing member includes a first end member including a first surface and a second surface, and a first side wall member having a ring shape and directly or indirectly connected to the first end member. The first side wall member includes a third surface on a side opposite to a side connected to a portion of the second surface. The second housing member includes a second end member including a fourth surface and a fifth surface facing a portion of the second surface, and a second side wall member having a ring shape and directly or indirectly connected to the second end member.