Lepidoptera fauna of five owl species nests were investigated in Japan. Seventeen moth species were identified: Niditinea striolella (Tineidae), Agonopterix sp. (Elachistidae) from Blakiston's Fish Owl, Ketupa blakistoni, nests; Monopis longella (= pavlovskii), M. flavidorsalis, M. sp., M. congestella, Niditinea baryspilas, N. striolella, N. sp. (Tineidae), Martyringa ussuriella (Oecophoridae), Mabra charonialis (Crambidae), Pyralis regalis (Pyralidae) from Ural Owl, Strix uralensis, nests; Tinea translucens, Niditinea baryspilas (Tineidae) from Brown Hawk-Owl, Ninox scutulata, nests; Opogona sacchari, O. sp., Phaeoses sp. (Tineidae) from Collared Scops Owl, Otus lempiji, nests; and Opogona sacchari, Phaeoses sp., Setomorpha sp. (Tineidae), Endotricha theonalis (Pyralidae) from Ryukyu Scops Owl, Otus elegans, nests. The moth nest fauna varied among owl species. The differences were related to owl prey (fish, small animals and birds, insects) and habitats (urban area, forest), and the tineid species selecting the nest. Tineids are presumed to decompose keratin found in owl nests and help maintain the cleanliness of the nest chamber, and such relationships between tineids and owls may be mutualistic. Rapid burrowing into owl nest materials by tineids may reflect a strategy to avoid being preyed upon by the nest owners.