Influx mouth possesses 4 and outlet 6 the housing to be received inside 2 which and housing 2, as the blood corpuscle component, includes the red corpuscle, the blood platelet and the leucocyte filters the blood which has with the filter section 7 which the blood processing filter 1 which, filter section 7 to capture the specified blood corpuscle component substantially from the blood, make the remaining blood corpuscle component pass on high-level side of the main filter section and the main filter section which be arranged substantially does not capture the blood corpuscle component with the pre- filter section which to have, as for the pre- filter section, with the head, mean particle diameter the particulate of 6 millimicronsWhen letting flow the suspensoid which is included, it features that transmissivity of the particulate is 70 - 90%.流入口4と流出口6を有するハウジング2と、ハウジング2内に収納され、血球成分として赤血球、血小板および白血球を含む血液をろ過するフィルター部7とを備える血液処理フィルター1であって、フィルター部7は、血液から実質的に所定の血球成分を捕捉し、残りの血球成分を通過させるメインフィルター部と、メインフィルター部の上流側に配置され、実質的に血球成分を捕捉しないプレフィルター部とを備え、プレフィルター部は、落差により、平均粒子径が6μmの微粒子を含む懸濁液を流したときの微粒子の透過率が70~90%であることを特徴とする。
