A method of enabling reuse of photographic processing waste solutions with ease at low cost without discharging effluents in a substantial sense, and a photographic processing agent regenerated by such a method are provided, which is a method of reusing a photographic processing waste solution, in which a solidified matter is prepared from the photographic processing waste solution by a dry-solidification according to a thin film concentration method without removing ingredients accumulated during a processing, the solidified matter is formed into granules, and the granules is reused as a solid photographic processing agent: and a regenerated processing agent prepared by the aforesaid method.