<p>A diaphragm valve can property mount a peripheral portion of a diaphragm over the entire periphery and certainly establish a seal between the peripheral edge portion on a surface side of the diaphragm and a diaphragm mounting seat for preventing leakage of a liquid. The diaphragm valve includes an annular base (27) provided to project from a seat surface of said mounting seat (12) for a predetermined height and connected with a bracket mounting flange (16) on the side of said valve operating portion by bolts (17) and a diaphragm retaining portion (30) formed integrally with said flange (16) for compressing the peripheral edge portion of said diaphragm with a constant pressure so that said flange (16) and said base (27) are connected by said bolts (17) in the condition where said diaphragm (14) is compressed onto said base (12) with said constant pressure by said diaphragm retaining portion (30). <IMAGE></p>
