Burdens on doctors and nurses are reduced in a blood purification therapy, and burdens on patients are also reduced while the cost reduction of the blood purification therapy is attained. A blood purification device 1 include a blood circuit 10 having two blood purifiers 20 and 21 parallelly connected thereto, switch means 11 capable of selectively supplying blood to the blood purifiers 20 and 21, and cleaning fluid supply means 12 capably of selectively supplying cleaning fluid to the blood purifiers 20 and 21. The cleaning fluid is supplied to the second blood purifier 21 while the blood is supplied to the first blood purifier 20, and the cleaning fluid is supplied to the first blood purifier 20 while the blood is supplied to the second blood purifier 21.
