A plasma purifying device is provided that is capable of recovering blood and plasma remaining within the plasma purifying device easily and without risk of coagulation, following completion of plasma purification therapy. The plasma purifying device has a control unit controls flow rates of the air pump and a plasma pump so that a pressure of the filtration side space of the plasma separator is higher than a pressure of the blood side space while delivering blood to the blood side space of the plasma separator by continuing to operate a blood pump without stopping following completion of plasma purification and then delivers plasma remaining in a filtration side space of a plasma separator to a blood side space of the plasma separator or to a plasma circuit by supplying air from an air pump.
