[Problem] To provide: a blood purifying device that is capable of sufficiently inspecting for liquid leakage at the entire duct of a blood circuit and a method for inspecting for liquid leakage in the blood purifying device. [Solution] The blood purifying device is equipped with: a blood circuit (1) that is configured from a vein-side blood circuit (1b) and an artery-side blood circuit (1a) and that is provided with a blood pump (2) a dialyzer (4) for purifying blood of a patient that circulates extracorporeally through the blood circuit (1) a dialysate introducing line (L1) that introduces a dialysate to the dialyzer (4) and a dialysate discharge line (L2) that discharges dialysate from the dialyzer (4). The blood purifying device is provided with: a pressure changing means that, in the state of the end of the artery-side blood circuit (1a) being connected to the end of the vein-side blood circuit (1b) forming a closed circuit wherein the blood circuit (1) is sealed, changes the pressure in the closed circuit and a liquid leakage detection means that detects that there is a liquid leak in the blood circuit (1) in accordance with the changes in pressure resulting from the pressure changing means.La présente invention vise à fournir un dispositif dépuration du sang qui est capable dune inspection adéquate pour détecter une fuite de liquide au niveau de lensemble du conduit dun circuit sanguin et un procédé pour linspection de fuite de liquide dans le dispositif dépuration du sang. À cet effet, linvention concerne un dispositif dépuration du sang équipé: dun circuit sanguin (1) qui est configuré à partir dun circuit sanguin côté veine (1b) et dun circuit sanguin côté artère (1a) et qui est muni dune pompe sanguine (2) dun dialyseur (4) pour lépuration du sang dun patient qui circule à lextérieur du corps à travers le circuit sanguin (1) dun conduit dintroduction de dialysat (L1) qui introduit un dialysat dans le dialyseur (4) et dun conduit de dévacuation de dialy
