lkei-jima is the northernmost island of the Katsuren Islands, situated north of the Yokatsu Peninsula of Okinawa Island. The vascular flora of lkei-jima was studied to gather data which serves as a basis for nature education in remote islands. A total of 372 species, one subspecies, four varieties, and two forms of vascular plants of 101 families were observed in the wild state on the island, of which 239 species, one subspecies, three varieties, and one form were native. Among all identified species, Balanophora fungosa, Excoecaria agalloicha, Suzukia luchuensis, and Solanum lyratum form. purpuratum were determined to be floristically noteworthy species because of their limited distributions. Solanum kayamae, an endemic species recorded in the southern and middle parts of Okinawa Island, was newly found from Ikei-jima and was treated as only a purple-flowered form, form. purpuratum, of Solanum lyratum in this study. The occurrence of Portulaca quadrifida, was confirmed by a herbarium specimen preserved in KAG. The naturalized plants accounted for 35.6 percent of the total wild plants found on the island.