A pharmaceutical preparation comprises nano-level particles (nanospheres) of a biocompatible polymer having, as held on their surfaces, an NFκB decoy capable of binding to NFκB to inhibit its activity. With penetration of the nanoparticles inside cells, the NFκB decoy may be delivered to an affected site and the NFκB decoy may be released from the surfaces of the nanoparticles and may be thereby efficiently and specifically introduced into the affected site.