Provided are a method of conveniently and efficiently removing abnormalprion protein from a blood product and a method of removing leukocytesimultaneouslywith abnormal prion protein. The method of removing an abnormal prion proteinfroma blood product includes filtering the blood product through a filter filledwith a carriercoated with a polymer, which is composed of three units including 20 mol% ormoreand 40 mol% or less of a unit originating from a hydrophobic polymerizablemonomer,mol% or more and 13 mol% or less of a unit originating from a polymerizablemonomer containing a basic nitrogen-containing part, and a unit originatingfrom apolymerizable monomer containing a protonic neutral hydrophilic part as thebalance,and then recovering the filtered blood product.
