PROBLEM TO BE SOLVED: To provide a blood purification device capable of easily and correctly determining propriety of fluid block by a check valve, before treatment.SOLUTION: A blood purification device comprises: a blood circuit； a dialyzer 1； a dialysis fluid introduction line L1 and a dialysis fluid discharge line L2； pressure detection means (&alpha；-&gamma；)； dialysis fluid take-out means 10； a dialysis fluid supply line La； and a check valve 18 for blocking flow of the fluid going from the blood circuit to the dialysis fluid introduction line L1. The blood purification device further comprises: control means 19 for generating pressure difference between the blood circuit side and the dialysis fluid introduction line L1 side sandwiching the check valve 18； monitor means 20 for monitoring change of a detection value of the pressure detection means based on pressure difference； and determination means 21 for determining propriety of fluid block by the check valve 18, based on change of the detection value of the pressure detection means.【課題】治療前に逆止弁による液体の遮断の適否を容易且つ正確に判定することができる血液浄化装置を提供する。【解決手段】血液回路と、ダイアライザ１と、透析液導入ラインＬ１及び透析液排出ラインＬ２と、圧力検出手段（α～γ）と、透析液取出手段１０と、透析液供給ラインＬａと、血液回路から透析液導入ラインＬ１に向かう液体の流れを遮断する逆止弁１８とを備えた血液浄化装置において、逆止弁１８を挟んで血液回路側と透析液導入ラインＬ１側との間で圧力差を生じさせ得る制御手段１９と、圧力差に基づく圧力検出手段の検出値の変化を監視し得る監視手段２０と、圧力検出手段の検出値の変化に基づいて、逆止弁１８による液体の遮断の適否を判定し得る判定手段２１とを具備したものである。【選択図】図１
