To provide a method of solidification treating waste solutions, by which the problems in the waste solution treatment, which problems are related to mini-laboratories and are such that the waste solution is difficult to handle, or the like, can be solved, and to provide a treating device.

The method of solidification treating a photographic waste solution is characterized in that a paper material is added and diffused into the photographic waste solution and then the paper material is utilized as a solidifying and bonding material of the photographic waste solution when the photographic waste solution is concentrated to solid by evaporation.