An endoscope reprocessor includes a concentration sensor 15 including a concave section in which a sensing section is housed and a permeable membrane 10 configured to cover the concave section, a medicinal solution tank 23, to an inside of which at least the permeable membrane 10 is exposed and on the inside of which a disinfection solution R is stored, and a heating section 30 configured to heat at least the permeable membrane 10.