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