Four species of Hylaeus are known to occur on the Bonin Islands: H. (Paraprosopis) yasumatsui, n. sp., H. ikedai (Yasumatsu), H. ( Nesoprosopis) honinensis Yasumatsu and H. incoinitatits, n. sp. These bees appear to represent a relict fauna with relationships from the Palearctic, Micronesian and Oriental Regions. The zoogeographic peculiarities of each species are discussed. All species are described and illustrated in detail and a key for their separation is provided.