To provide blood component separation device, blood constituent can be each separated with blood constituent separation method and is virus inactivated processing blood constituent rapidly from blood from blood. The embodiment that blood component separation device (1) discloses includes: blood constituent separation area (12A), it is provided in centrifuge (12), for separating blood constituent from blood by centrifugal blood, it is collected in blood from blood donor Dilution part (diluent memory paragraph (15), dilute path (T7), the 6th pump (P6)) it dilutes, riboflavin is contained in dilution, the red blood cell of concentration separates, by blood constituent separation area (12A) Ultraviolet light transmitting unit (16) is virus inactivated processing, is therefore diluted by the red blood cell of emitting ultraviolet light to concentration.
