PROBLEM TO BE SOLVED: To provide a blood purification device capable of maintaining a constant amount of air, the air being introduced from an opening part, during liquid leakage prevention operation.SOLUTION: A blood purification device comprises: a dialysate introduction line L1 for introducing a dialysate to a dialyzer 9； a dialysate discharge line L2 for discharging the dialysate introduced by the dialysate introduction line L1 from the dialyzer 9； connection tools C1, C2 for optionally switching a connection state in which, a closed circuit is formed by the dialysate introduction line L1 and dialysate discharge line L2, and an open state in which the closed circuit is opened for forming an opening part； and control means 8 for making perform liquid leakage prevention operation for introducing outside air from the opening part. Air detection means capable of detecting air introduced from the opening part is provided in the vicinity of the connection tools C1, C2, and control means 30 stops the liquid leakage prevention operation under the condition that the air is detected by the air detection means.SELECTED DRAWING: Figure 1【課題】液こぼれ防止動作時、開放部から導入される空気の量を一定化することができる血液浄化装置を提供する。【解決手段】ダイアライザ９に透析液を導入し得る透析液導入ラインＬ１と、透析液導入ラインＬ１にて導入された透析液をダイアライザ９から排出し得る透析液排出ラインＬ２と、透析液導入ラインＬ１及び透析液排出ラインＬ２で閉回路を形成させる接続状態と、当該閉回路を開放して開放部を形成させる開放状態とを任意に切換可能な接続具Ｃ１、Ｃ２と、開放部から外部の空気を導入する液こぼれ防止動作を行わせ得る制御手段８とを具備した血液浄化装置であって、接続具Ｃ１、Ｃ２の近傍に開放部から導入した空気を検知可能な空気検知手段を備えるとともに、制御手段３０は、当該空気検知手段で空気が検知されたことを条件として、液こぼれ防止動作を停止させるものである。【選択図】図１
