The invention provides a blood processing filter and a blood filtering method adopting the same. The blood processing filter includes the flexible container having an inlet and an outlet for blood and the sheet-like blood processing filter material which is arranged to separate the inside of the container into the inlet side and the outlet side, wherein the flexible container includes a container body for accommodating the blood processing filter material and an inlet side port which is fixed to the container body to form the inlet or outlet, the inlet side port has an inlet side main tube section connected to a conduit that transports the blood and a fixed part which communicates the inlet side main tube section into the container body and fixes the inlet side main tube section to the outer surface of the container body, and the axis of main tube section inclines relative to the tangent of the outer surface of the container body.
