The invention is a blood purification device (1A) provided with a blood circuit (20) having a blood removal side circuit (2), which pumps blood taken from the subject (100) to a plasma separator (5) and a re-infusion side circuit (12), which returns blood that has passed through the plasma separator (5) back to the subject (100)； a circulating circuit (14) that connects the re-infusion side circuit (12) to the blood removal side circuit (2)； a plasma circuit (6A), which pumps plasma components separated in the plasma separator (5)； and a control unit (16), which controls the blood flow so that when blood is being pumped in the blood circuit (20) and a portion of the plasma components separated in the plasma separator (5) is being pumped to the plasma circuit (6A), a portion of the blood flowing in the re-infusion circuit (12) is circulated to the circulating circuit (14) to merge with the blood removal side circuit (2).本發明係一種血液淨化裝置1A，該血液淨化裝置1A包含：血液迴路20，其係包含將自檢體100取出之血液輸送至血漿分離器5之脫血側迴路2、及將通過血漿分離器5之血液回輸至檢體100之還血側迴路12；循環迴路14，其係連接還血側迴路12與脫血側迴路2；血漿迴路6A，其係輸送由血漿分離器5分離之血漿成分；及控制部16，其係輸送血液迴路20內之血液，且於由血漿分離器5分離之一部分血漿成分輸送至血漿迴路6A之狀態下，以使還血側迴路12中流動之血液之一部分於循環迴路14內進行循環並匯流至脫血側迴路2之方式控制血液之流動。
