A blood purification device 1A includes: a blood circuit 20 including a blood removal-side circuit 2 that carries blood taken from a subject 100 to a plasma separator 5, and a blood reinfusion-side circuit 12 that returns the blood passing through the plasma separator 5 to the subject 100； a circulating circuit 14 that connects the blood reinfusion-side circuit 12 to the blood removal-side circuit 2； a plasma circuit 6A that carries plasma components separated by the plasma separator 5； and a control unit 16 that controls blood flow so that a portion of the blood flowing in the blood reinfusion-side circuit 12 is circulated to the circulating circuit 14 to be flown to the blood removal-side circuit 2 when the blood in the blood circuit 20 is being pumped and a portion of the plasma components separated by the plasma separator 5 is being pumped to the plasma circuit 6A.
