An air purification system comprises: a duct working as an air-flow path; an air-conditioning unit having an air purification filter provided on the duct; and a blower fun. The air purification filter contains an antibody material. The antibody material comprises: the blood components of a livestock animal which is administered desired antigens such as bacteria, mold, virus and environmental allergen; and/or a livestock food product containing that blood components. The blood components and the livestock food products are contained in the antibody material as effective components.