Copromorpha kijimuna sp. nov., which is closely related to C. pleurophanes Meyrick (Copromorphidae), is described from the Ryukyus, Japan, with illustrations of the adult stage, including its genitalia, and of the immature stage. The larva bores into the fruit of Ficus virgata (Moraceae). Descriptions of the immature stages of the genus are given for the first time. The lectotype of C. pleurophanes, including its genitalia, is illustrated. Both the family and the genus are newly added to the Japanese moth fauna. Autapomorphies for the Copromorphidae are proposed on the basis of larval and pupal characters.