Abstract: A throttle valve is provided with a heater for keeping an external surface of a valve disc and an adjacent thereto internal surface of a flange portion at high temperature to prevent deposition of fine particles contained in etching gas, and thereby the said valve may provide smooth and reliable adjustment of the valve opening over the long period of its operation.The valve controls the flow of gas along a pipe by changing the open area of a fluid passage formed therein through the valve disc 2 which is turned by driving shaft 3 from driving means provided in a driving portion 4. The valve disc 2 is heated with a heating rod 6 mounted therein. Plate-like heaters 20.sub.1 and 20.sub.2 are mounted on the flange portion 1b of the valve 1 to heat the flange portion 1b and valve disc 2. The external surface of the valve disc 2 and the internal surface of the flange portion are heated to prevent adhesion of dust particles thereto. Therefore, the valve disc 2 can smoothly move with no obstruction.