To enable to remove viral envelope from blood, plasma, or serum by using at least one kind of polyaniline, one kind of deposit filter, and a composition containing one kind of polyaniline bonding adsorption substance.

Polyaniline and especially heparin are added to a deposit buffer within the H.E.L.P method. A complex of polyaniline and viral envelope is effectively deposited. The deposit is rejected through a deposit filter. A fluid composed of blood, plasma, or serum, which is diluted by the buffer and containing an excessive amount of polyaniline, is passed through a polyaniline bonding adsorption substance. The excessive amount of polyaniline is removed, and a dialysis is carried out to generate blood so that the blood is restored to its original viscosity. At last, the blood, from which viral envelope has been substantially removed, is adjusted to a physiological pH, and then returned to a patient.