The endoscope reprocessor of the present invention includes a storage container that stores a solution, a fluid supply unit that supplies the solution into the storage container, a fluid discharge unit that discharges the solution from the storage container, and the storage A concave liquid reservoir that is fixed in the container and whose bottom surface is located below the opening in the direction of gravity, and at least a portion of the first surface exposed in the liquid reservoir is below the opening in the direction of gravity. A permeable membrane located in the container, a container-like accommodation portion including at least a part of the second surface opposite to the first surface of the permeable membrane as an inner surface, an internal liquid accommodated in the accommodation portion, and A densitometer including an electrode housed in the housing portion.本発明の内視鏡リプロセッサは、溶液を貯留する貯留容器と、前記貯留容器内に前記溶液を供給する流体供給部と、前記貯留容器内から前記溶液を排出する流体排出部と、前記貯留容器内に固定され、底面が開口部よりも重力方向下方に位置する凹形状の液溜まり部と、前記液溜まり部内に露出する第１の面の少なくとも一部が前記開口部よりも重力方向下方に位置する透過膜、前記透過膜の前記第１の面とは反対側の第２の面の少なくとも一部を内面として含む容器状の収容部、前記収容部内に収容される内部液、及び、前記収容部内に収容される電極、を含む濃度計と、を有する。
