There is provided a preparation process in which a N—H group of a heteroaromatic ring compound having a N—H group in its ring is converted directly to a N—Rf group at a high reaction efficiency without using a catalyst. The preparation process is a process for preparing a compound comprising a heteroaromatic ring structure having a N—Rf group (—Rf is a fluorine-containing organic group) in its ring and is characterized in that the heteroaromatic ring compound having a N—H group in its ring is allowed to react with fluoroalkene in the absence of an alkali metal.