A new species of the genus Scaptognathus is described from Okinawa under the name of Scaptognathus okinawensis sp. nov. This species is most related to S. kunzi which has been recorded from Hawaii and Great Barrier Reef, but distinguished from the latter by the round ocular plate, rounded anterior margin of posterodorsal plate, and smaller size of anterior sclerosum of tripartite genitoanal plate.