The to thin film being the polysulfone hollow yarn membrane which is converted, the porous hollow yarn membrane for the blood processing where production process and while transporting or you handle and the time is difficult to cause the mechanical damage, furthermore in cutoff characteristic is superior is offered. Including with the polysulfone polymer and poly- vinyl pyrolidone, from inside film thickness direction directing outside and the said porous structure film thickness is under 40 millimicron of 25 millimicrons or more in the porous hollow yarn membrane for blood processing which forms the gurajiento porous structure which diameter expands, at the same time, in order all the average thicknesses the fibril of 100 - 200 millimicrons, outer part average thickness of film thickness direction (To) with the inside average thickness (Ti) ratio (To/Ti) to become 2 or less, being arranged the porous hollow yarn membrane for blood processing which features that it becomes.薄膜化されたポリスルホン系中空糸膜であっても、生産工程や移送中あるいは取扱い時に機械的損傷を生じ難く、しかも分画性に優れる血液処理用の多孔質中空糸膜を提供する。ポリスルホン系ポリマーとポリビニルピロリドンとを含み、膜厚方向の内側から外側に向けて孔径が拡大するグラジェント多孔質構造を成す血液処理用多孔質中空糸膜において、該多孔質構造は膜厚が25μm以上40μm未満であり、かつ、全平均太さが100~200μmのフィブリルが、膜厚方向の外側平均太さ(To)と内側平均太さ(Ti)の比(To/Ti)が2以下となるように配置されてなることを特徴とする血液処理用多孔質中空糸膜。
