A porous aluminum fluoride on which SbCl.sub.xF.sub.5-x (wherein x represents a numeral of 0 to 5) is supported, SbCl.sub.xF.sub.5-x being obtainable by supporting SbCl.sub.5, or the like on a porous aluminum fluoride and treating it with hydrogen fluoride. The resulting porous aluminum fluoride has a high activity as a fluorinating agent, a fluorination catalyst, or the like, is easy to handle, can be used for a flow-type reaction, and also can be used even at a high temperature.