A process for dehydrating a hydrofluorocarbon or hydrochlorofluorocarbon, which can be done by simple equipment, and a continuous process of producing 1,3,3,3-tetrafluoropropene using the dehydration process. The dehydration process includes cooling the hydrofluorocarbon or hydrochlorofluorocarbon in gaseous form containing water with a heat exchanger, thereby condensing and liquefying the hydrofluorocarbon or hydrochlorofluorocarbon while freezing and solidifying the water. The 1,3,3,3-tetrafluoropropene production method includes a first step for fluorinating 1-chloro-3,3,3-trifluoropropene with hydrogen fluoride to obtain a mixture of 1,3,3,3-tetrafluoropropene, unreacted 1-chloro-3,3,3-trifluoropropene, hydrogen fluoride, hydrogen chloride and by-products, or dehydrofluorinating 1,1,1,3,3-pentafluoropropane to obtain a mixture of 1,3,3,3-tetrafluoropropene, unreacted 1,1,1,3,3-pentafluoropropane and by-products, a second step for removing acidic components, a third step for dehydrating the 1,3,3,3-tetrafluoropropene by the above dehydration process, and a fourth step for purifying the 1,3,3,3-tetrafluoropropene by distillation.