The diet of the Orii's flying-fox, Pteropus dasymallus inopinatus, a subspecies of the Ryukyu flying-fox, was investigated on Okinawa-jima Island, Japan. The Orii's flying-fox is a generalist forager that feeds on 78 plant species from 62 genera and 43 families. They consume fruits of 53 species, flowers of 20 species, and leaves of 18 species. Cultivated or naturalized plants composed almost half of the diet. Diversity in the diet may be an adaptation to unstable food conditions on this small subtropical island. The number of individual Orii's flying-foxes fluctuated greatly corresponding to monthly changes in food availability, especially that of Ficus microcarpa, which was the animal's main food resource throughout the year. Orii's flying-foxes may adapt to an urban environment by intensively using areas with abundant planted trees.