The purpose of the present invention is to automatically remove air bubbles while keeping cleanliness of a blood purification device when air bubbles are detected during priming the device. A blood purification device 1 is equipped with: a blood purifier 10； a washing liquid reservoir 20 having a washing liquid stored therein； a washing flow path 30 that connects the blood purifier 10 and the washing liquid reservoir 20 to each other； a detector 40 provided on the washing flow path 30 for detecting air bubbles； a discharge flow path 50 communicated with the blood purifier 10 for discharging the washing liquid； a transfusion reservoir 60 for storing a transfusion therein； a pump 80 provided on a flow path between the detector 40 and the transfusion reservoir 60； and a control unit 90 that activates the pump 80 so as to supply the transfusion from the transfusion reservoir 60 to the washing liquid reservoir 20 via the detector 40 when the detector 40 detects air bubbles.
