PROBLEM TO BE SOLVED: To provide a blood purification device capable of immediately supplying dialysis fluid in a dialysis introduction line to a blood circuit in the middle of an ultrafiltration treatment without performing a preparatory operation for fluid replenishment, or immediately supplying dialysis fluid in the dialysis introduction line to the blood circuit after the ultrafiltration treatment for returning blood.SOLUTION: A blood purification device includes a dialyzer 1 for purifying blood flowing in a blood circuit, a dialysis fluid introduction line L1 capable of introducing dialysis fluid to the dialyzer 1, a dialysis fluid discharge line L2 capable of discharging waste fluid from the dialyzer 1, and a water removal pump 10 capable of removing water from the blood flowing in the blood circuit, and can supply dialysis fluid in the dialysis fluid introduction line L1 to the blood circuit for performing fluid replenishment or blood returning. When an ultrafiltration treatment in which, while introduction of dialysis fluid to the dialyzer 1 is stopped, the water removal pump 10 is driven for removing water, is carried out, supply of dialysis fluid is performed while inflow of dialysis fluid to the dialyzer 1 is regulated.SELECTED DRAWING: Figure 4【課題】準備運転を経ることなく、限外濾過治療の途中で透析液導入ラインの透析液を血液回路に直ちに供給して補液を行い、又は限外濾過治療の後に透析液導入ラインの透析液を血液回路に直ちに供給して返血を行うことができる血液浄化装置を提供する。【解決手段】血液回路を流れる血液を浄化するダイアライザ１と、ダイアライザ１に透析液を導入し得る透析液導入ラインＬ１と、ダイアライザ１からの排液を排出し得る透析液排出ラインＬ２と、血液回路を流れる血液から除水し得る除水ポンプ１０とを具備し、透析液導入ラインＬ１の透析液を血液回路に供給して補液又は返血が可能とされた血液浄化装置であって、ダイアライザ１に対する透析液の導入を停止しつつ除水ポンプ１０を駆動させて除水する限外濾過治療が行われる際、ダイアライザ１に対する透析液の流入を規制しつつ透析液の送液を行わせるものである。【選択図】図４
