A body fluid treating filter device capable of maintaining its treating pressure within a clinically safe pressure range even if body fluid treatment is performed over a long period and having excellent property for recovering a body fluid after the body fluid treatment is completed. A body fluid treating cylindrical filter layer is stores in a cylindrical container having two body fluid flow ports. The cylindrical filter layer is disposed so that the inner space of a container can be divided into two parts by making its both end parts fluid-tight and fixing at least one of these both end parts to the inner wall surface of the container. One of the inner spaces of the container divided by the cylindrical filter layer is allowed to communicate with the first body fluid flow port and the other of the inner spaces of the container divided by the cylindrical filter layer is allowed to communicate with the second body fluid flow port. The body fluid treating cylindrical filter device is characterized in that a bar-like flow passage resistant member extending along the center axis is installed in the hollow part of the cylindrical filter layer, and a spacer layer for flowing the body fluid of 0.7 to 3.5 mm in thickness is formed between the outer peripheral surface of the cylindrical filter layer and the container and between the inner peripheral surface of the cylindrical filter layer and the flow passage resistance member.
