A valve (10) includes a first case member (101) having an inflow port (H1) and a first valve seat (VS), a second case member (105) having an air outlet (H2) and a discharge port (H3), a valve chamber formed by bonding the first case member (101) and the second case member (105), at least one of which has a recessed shape, with a first bonding member (300) while the recessed shape is located on an inner side, and a diaphragm (150) formed so as to partition the valve chamber into a lower valve chamber (106) connected to the inflow port (H1) and an upper valve chamber (107) connecting the discharge port (H3) and the air outlet (H2).