An object of the present invention is to provide a filter built in a blood purification column, which drastically improves the removal performance of air mixed in the column, and can be used for activating blood by the air remaining in the column, It is to prevent deterioration of adsorption performance due to reduction of contact area. What is claimed is: 1. An absorbent article comprising: an adsorbent and a casing having open ends at both ends thereof, wherein an adsorbent is accommodated inside the casing, one of both ends of the casing is an end portion on the blood inflow side and the other is a blood outflow end, Wherein a filter is disposed at an end portion on the blood inflow side and / or an end portion on the blood outflow side of the blood purification column, and the filter satisfies the following requirements.(1) the aperture ratio is 5% or more and 80% or less(2) the equivalent diameter of its mesh opening is 1 m or more and 5000 m or less(3) The ratio of the equivalent diameter of the mesh opening to the average equivalent circle diameter of the gap of the adsorbent is 45% or more本発明の課題は、血液浄化カラムに内蔵されるフィルタに関し、カラム内に混入したエアの抜け性を飛躍的に向上させ、カラム内に残存したエアによる血液活性化や、吸着体と血液との接触面積の減少による吸着性能低下を防ぐことである。 吸着体と、両端が開放端であるケーシングとを有し、前記ケーシングの内部に吸着体が収容され、前記ケーシング両端の一方が血液流入側端部、他方が血液流出端部であり、前記ケーシングの血液流入側端部および/もしくは血液流出側端部にフィルタが配置され、前記フィルタは以下の要件を満たす血液浄化カラム。(1)その開口率が5%以上、80%以下(2)その目開きの相当直径が1μm以上、5000μm以下(3)その目開きの相当直径の前記吸着体の間隙の平均円相当直径に対する比率が45%以上
