<Project>
A control valve having a diaphragm as a pressure member, while largely securing the valve opening degree, and improve the durability of the diaphragm and characters.
<MEANS FOR SOLVING PROBLEMS]>
Control valve according to one embodiment is provided with a shaft for transmitting the driving force in the axial direction by the displacement of the contact disc 29 and the diaphragm 28 per a coaxial form to the diaphragm 28 to the valve body. Diaphragm 28, the disk 29 is a waveform portion (62) between the flat portion 64 and the outer peripheral portion (66) comprising a contact face in contact with each party. Waveform section 62, the mountain which protrudes to the one side of the outer peripheral portion 66 with the reference surface 70, is formed by being substantially provided N + 0.5 more toward the flat portion 64 at the outer peripheral portion 66 ( N is a natural number). The height of the corrugation portion (62) Acid 72 between the diaphragm 28 as a, the outer peripheral portion 66 and the flat portion 64 with respect to a height relative to the reference plane 70 according to the no-load condition, is used it is configured to be smaller than the height of the flat portion (64).