A solid catalyst used in, for example, production of a perfluoroalkyl iodide telomer is effectively and continuously recovered and the recovered catalyst is continuously recycled to the reactor for reuse. A slurry containing a reaction product and the catalyst is drawn from the reaction system, and the catalyst in the drawn slurry is classified by means of a hydrocyclone, whereby a high-concentration slurry whose catalyst concentration is higher than that of the drawn slurry and a low-concentration slurry whose catalyst concentration is lower than that of the drawn slurry are obtained, and the high-concentration slurry is recycled to the reaction system.