An endoscope reprocessor includes: a medicinal solution storage portion configured to store a medicinal solution; a sampling tube including a first end portion opened inside the medicinal solution storage portion, and a second end portion opened outside the medicinal solution storage portion; a first chamber, inside which the second end portion of the sampling tube is opened; a second chamber where an opening portion and a communication port communicated with the first chamber are formed; a constricted portion configured to connect the first chamber and the communication port; a first advancing/retreating portion configured to advance and retreat between a first position to block the constricted portion and a second position to open the constricted portion inside the first chamber.