Abstract: A diaphragm valve includes a first valve housing, a diaphragm, a drive member, and a second valve housing. The diaphragm has a second abutting surface opposed to a first abutting surface, and a sealing portion formed on a position surrounding a second abutting surface. The diaphragm has an elastic coupling portion that elastically deforms and couples the second abutting surface to the sealing portion to cause the second abutting surface to move to a side of the first valve housing with respect to the sealing portion. The elastic coupling portion has a concave curved surface having a curved surface shape that is concave to a side of the second valve housing. The second valve housing has a supporting portion having a second convex curved surface having a curved surface shape that is convex to a side of the elastic coupling portion on a position opposed to the concave curved surface.