An endoscope reprocessor includes a concentration meter including a permeation membrane, a medicinal-solution storing section including a holding section configured to hold the concentration meter such that the permeation membrane is disposed at a predetermined water level, the medicinal-solution storing section storing the medicinal solution to a water level higher than the predetermined water level, a liquid discharge section configured to discharge the medicinal solution from the medicinal-solution storing section, a liquid supply section configured to supply liquid to the permeation membrane of the concentration meter, and a control section connected to the liquid discharge section and the liquid supply section, the control section driving the liquid supply section to wet the permeation membrane when the medicinal solution in the medicinal-solution storing section is lower than the predetermined water level.
