An endoscope reprocessor includes: a concentration measurement chamber； a liquid concentrate supply unit； a diluent supply unit； a holding unit configured to hold a concentration sensor； a memory； and a processor configured to produce information on a temporary standard curve based on a first point at which a first concentration is associated with a sensor output value at measurement of concentration of liquid concentrate and a second point at which a second concentration is associated with a sensor output value at measurement of concentration of a practical use solution after dilution, calculate a deviation degree between a standard curve and the temporary standard curve, and determine whether the temporary standard curve is valid from the deviation degree.
