A valve includes a first case member having an inflow port and a first valve seat, a second case member having an air outlet and a discharge port, a valve chamber formed by bonding the first case member and the second case member, at least one of which has a recessed shape, with a first bonding member while the recessed shape is located on an inner side, and a diaphragm formed so as to partition the valve chamber into a lower valve chamber connected to the inflow port and an upper valve chamber connecting the discharge port and the air outlet.