An endoscope reprocessor according to the present invention includes a densitometer including a housing having a hollow, a permeable membrane covering the recess, and an internal liquid stored in the recess and a controller configured to store the liquid to be measured, A tank for holding the densitometer so that the permeable membrane comes into contact with the liquid, a first adjustment unit for adjusting the pressure of the internal liquid, a second adjustment unit for adjusting the pressure of the liquid to be measured, A first state in which the pressure of the liquid is the first pressure and the pressure of the liquid to be measured is the second pressure and a third state in which the pressure of the internal liquid is lower than the first pressure, A control unit that controls the first adjustment unit and the second adjustment unit so that the first state is a second state in which the pressure of the second state is a fourth pressure lower than the second pressure Part.本発明の内視鏡リプロセッサは、くぼみを有するハウジング、前記くぼみを覆う浸透膜、および前記くぼみの中に貯留された内部液、を含む濃度計と、測定対象液を貯留し、前記測定対象液に前記浸透膜が接触するように前記濃度計を保持するタンクと、前記内部液の圧力を調整する第1調整部と、前記測定対象液の圧力を調整する第2調整部と、前記内部液の圧力が第1圧力であり、前記測定対象液の圧力が第2圧力である第1状態、および前記内部液の圧力が前記第1圧力よりも低い第3圧力であり、前記測定対象液の圧力が前記第2圧力よりも低い第4圧力である第2状態となるよう、前記第1調整部および前記第2調整部を制御する制御部と、前記第2状態を所定時間維持する維持部と、を含む。
