An object of the invention is to provide a process for preparing a fluorine compound, which can easily provide the objective fluorine compound using an oxygen-containing compound as a raw material without forming water as impurities as a by-product. The process for preparing a fluorine compound according to the invention includes reacting an oxygen-containing compound, which is at least one kind selected from the group consisting of oxides, hydroxides, hydrates, carbonic acid compounds, hydrogencarbonic acid compounds, boric acid compounds, sulfuric acid compounds, sulfurous acid compounds, phosphorous acid compounds and phosphoric acid compounds of at least any one kind selected from the group consisting of metal elements, H, B, C, N, Si, P, S, As, Se, Te and halogens, at least with carbonyl fluoride to form at least a fluorine compound and carbon dioxide without forming water as a by-product.