To provide a new system capable of efficiently removing an Aβ oligomer in the blood.SOLUTION: An amyloid-β (Aβ) removal system comprises a device that includes a hollow fiber membrane and the albumin permeability of which is in the range of 3-96%. Blood plasma separated from the blood passes from a hollow fiber membrane lumen to an outer surface of the hollow fiber membrane so as to remove an Aβ oligomer in the blood. Additionally, the blood plasma passes from the hollow fiber membrane lumen to the outer surface of the hollow fiber membrane while a liquid existing in the hollow fiber membrane lumen is partially discarded. Thus, the Aβ oligomer is accumulated in the liquid existing in the hollow fiber membrane lumen.SELECTED DRAWING: Figure 1【課題】血液中Ａβオリゴマを効率的に除去できる新たなシステムを提供する。【解決手段】アミロイド－β（Ａβ）除去システムは、中空糸膜を含み、アルブミンの透過率が３～９６％であるデバイスを有し、血液から分離された血漿を中空糸膜内腔から中空糸膜外面に通液させることで血中Ａβオリゴマを除去する。また、中空糸膜内腔に存在する液の一部を廃棄しながら、血漿を中空糸膜内腔から中空糸膜外面に通液させて、中空糸膜内腔中に存在する液中にＡβオリゴマを蓄積させる。【選択図】図１
