PURPOSE: To prevent the impossibility of valve operation by precipitation of calcium by making a partition part between fluid passages with a bellows partition member fixed between a valve body and a casing, thereby eliminating the presence of sliding part between the partition member and a valve stem.

CONSTITUTION: Two systems of fluid delivery parts 3b, 4b are connected to fluid passages 3, 4, of a flow controller, respectively. When the lower stream of the delivery part 3b is closed in the state where the fluid passages 3, 4 supply a fluid, the pressure of the delivery part 3b is raised, and the fluid flows into a control chamber 7 through a passage 9 to raise the pressure in the chamber. Consequently, a diaphragm 5 and a valve stem 8 combined thereto are lowered, and respective control parts 3c, 4c are simultaneously closed by valve bodies 8a, 8b. As a flexible bellows partition member 2 moves following the valve stem 8 at the time of opening and closing movement of the valve stem 8 as described above, no sliding part is present between the partition member 2 and the valve stem 8. Thus, no trouble of valve operation by precipitation of calcium is caused.