The present invention provides a method for inexpensively, efficiently, safely, and continuously producing Carbonyl fluoride, without using highly toxic raw materials such as phosgene or difficult-to-get raw materials, with no risk of explosion or the like. Tetrafluoroethylene gas and oxygen gas are introduced into a reactor, and they are then heated in a gas phase in the absence of nitrogen gas for reaction, so as to produce carbonyl fluoride. The reactor is preferably a tubular reaction tube. As such tetrafluoroethylene gas, unpurified or purified tetrafluoroethylene gas obtained by heating HCFC-22 gas for thermal decomposition can be used. According to the present invention, Carbonyl fluoride that is useful as cleaning gas for CVD devices (chemical vapor deposition method) can be inexpensively, efficiently, and safely produced.