PROBLEM TO BE SOLVED: To provide a method for reducing liquid in circuits of a blood purification device that even enables discharge of liquid in a replenishment liquid supply circuit and enables automation of liquid discharge while maintaining safety of a patient, without complicating a device configuration.SOLUTION: A method in the invention includes: a first step of reducing liquid in the dialysate supply circuit 13 by delivering liquid remaining in the dialysate supply circuit 13 into a secondary side 10b of a blood purifier 11 and delivering the liquid in the secondary side 10b to a side of a waste liquid circuit 14 a second step of reducing liquid in a replenishment liquid supply circuit 15 by, while keeping each closing part of a blood collection circuit 20 and the blood returning circuit 21 closed, delivering liquid remaining in the replenishment liquid supply circuit 15 into a blood returning circuit 21, delivering the liquid in the blood returning circuit 21 into a primary side 10a of the blood purifier 11, delivering the liquid in the primary side 10a into the secondary side 10b and delivering the liquid in the secondary side 10b to the side of the waste liquid circuit 14 and a third step of reducing the liquid in the waste liquid circuit 14 by delivering the liquid remaining in the secondary side 10b of the blood purifier 11 and in the waste liquid circuit 14 into a waste liquid part 60.COPYRIGHT: (C)2014,JPO&INPIT【課題】装置構成を煩雑化することなく、補液供給回路の液体も排出可能で、なおかつ患者の安全性を確保して液体の排出を自動化可能な、血液浄化装置の回路の液体を減らす方法を提供する。【解決手段】本発明は、透析液供給回路13内の残存する液体を、血液浄化器11の二次側10bに流し、二次側11bの液体を廃液回路14側に流して、透析液供給回路13内の液体を減らす第1の工程と、採血回路20と返血回路21の各閉鎖部を閉鎖した状態で、補液供給回路15内に残存する液体を、返血回路21に流し、返血回路21の液体を血液浄化器11の一次側10aに流し、一次側10aの液体を二次側10bに流し、二次側10bの液体を廃液回路14側に流して、補液供給回路15内の液体を減らす第2の工程と、血液浄化器11の二次側10b及び廃液回路14内に残存する液体を、廃液部60に流して、廃液回路14内の液体を減らす第3の工程と、を有する。【選択図】図1