An endoscope reprocessor of the present invention includes a reservoir configured to store a solution, a fluid supply section configured to supply the solution into the reservoir, a fluid discharge section configured to discharge the solution from the stored solution, a recessed pool section fixed inside the reservoir and having a bottom surface positioned below an opening section in a gravitational direction, and a concentration meter including a permeable membrane having a first surface exposed inside the pool section, at least a part of the first surface being positioned below the opening section in the gravitational direction, an accommodation section having a container shape and including a part of a second surface of the permeable membrane as an inner surface, the second surface being on an opposite side to the first surface, internal liquid accommodated in the accommodation section, and an electrode accommodated in the accommodation section.
