It is an object of the present invention to provide at low costs a valve with an integral orifice for use in a gas feeding equipment provided with a pressure-type flow volume control device to be employed for manufacturing of semi-conductors and chemical goods. The valve with an integral orifice has the excellent flow rate control characteristics by improving the processing accuracy of the orifice and preventing the distortion of the orifice at the time of assembling. To realize the objects of the present invention, the main part of the valve with an integral orifice comprises a valve main body made of heat-resisting materials having a gas inflow passage in communication with a valve chamber with an upper open end and a gas outflow passage, a synthetic resin made valve seat body formed in the valve chamber and having a gas outflow passage in communication with the gas outflow passage of the aforementioned valve main body and a valve seat, an orifice disc made of heat-resisting materials removably installed in the gas outflow passage of the valve seat body, and an orifice formed in the orifice disc to reduce the gas outflow passage of the valve seat body; wherein the orifice is formed in the stainless steel made orifice disc in advance and the metal made orifice disc with the orifice formed by a separate processing and the synthetic resin made valve seat body are removably assembled, wherein the orifice disc and the synthetic resin made valve seat body are fixed airtight to the valve main body by pressing the valve seat body via the metal inner disc.