Abstract: Provided is a functional air filter which can maintain a sufficient function of suppressing breeding of mold and undesired bacteria for a long period thus being hygienic, exhibiting high safety and possessing deodorizing property. In a functional air filter which is manufactured by, at intersections between wefts and warps made of a thermoplastic sheath-core type composite monofilament which is a composite fiber consisting of a core material and a sheath material made of a resin having a lower melting point than the core material, heat-fusing the sheath materials to each other, the composite monofilament is configured such that some particles blended into the sheath material are exposed from a surface of the sheath material. The particle is a mixed particle where fine particles are fixedly adhered to a surface of a coarse particle.