Abstract: A filter assembly for an air purifier is provided. The filter assembly includes base plates that are curved and have a lamp insertion hole formed at its center so that an ultraviolet (UV) lamp can be inserted thereto, a gap retaining member that keeps the base plates spaced apart from each other and combined with each other. Surfaces of the base plates are coated with either a photocatalyst material and silver nanoparticles. According to the filter assembly, the sterilizing and disinfecting capability can be enhanced by increasing a contact area between each of base plates and silver nanoparticles. In addition, since the filter assembly is easily assembled, length adaptability of the filter assembly can be achieved.