This is the first revision of the family Colletidae of Japan. Two subfamilies, Colletinae and Hylaeinae, are recogniszed, including each one genus, Colletes and Hylaeus, respectively. In Japan, the genus Colletes Latreille includes 6 species, and the genus Hylaeus Fabricius does 23 species. Allthe species are described and illustrated.Most of the species are assigned to the subgenus for the first time. The classification and phylogeny are discussed for the family, the genera and the subgenera. Keys are provided for the species of the genus Colletes, and for the subgenera and species of the genus Hylaeus.The Japanese subgenera here recognized are Colletes Latreille, belonging to the genus Colletes, and Hylaeus Fabricius, Nesohylaeus (new subgenus), Prosopis Fabricius, Nesoprosopis perkins, Paraprosopis Popov, Lambdopsis Popov and Patagiata Blüthgen, belonging to the genus Hylaeus. The 4 subgenera of Hylaeus except for Nesoprosopis and Paraprosopis are newly recorded from Japan.The following species are assigned to the subgenus for the first time: C. (Colletes) perforator Smith, 1869, C. (Colletes) eskii Hirashima, 1958, C. (Colletes) babai Hirashime et Tadauchi, 1979, H. (Hylaeus) perforatus (Smith), 1873, H. (Hylaeus) paulus Bridwell, 1919, H. (Nesohylaeus) niger Bridwell, 1919, H. (Prosopis) monticola Bridwell, 1919, H. (Paraprosopis) meridianus Yasumatsu et Hirashima, 1965, H. (Paraprosopis) incomitatus Snelling, 1970, and H. (Lambdopsis) nipponicus Bridwell, 1919.The species belonging to the subgenus Colletes are divided into four species groups, and those of Nesoprosopis are divided into two species groups.Seven new species are described. They are: C. (Colletes) yasumatsui Hirashima et Ikudome, H. (Prosopis) submonticola, H. (Paraprosopis) Hirashimai, H. (Paraprosopis) thoracicus, H. (Patagiata) paradifformis, H. nanseiensis and H. macilentus.The males of the following five species and a subspecies are described for the first time: C. (Colletes) esakii Hirashima, H. (hylaeus) paulus Bridwell, H. (Hylaeus) perforatus (Smith), H. (Paraprosopis) meridianus Yasumatsu et Hirashima, H. (Paraprosopis) incomitatus Snelling and H. (Nesoprosopis) insularum iriomotensis Yasumatsu et Hirashima.The subgeneric status of the following three species is unknown: H. ikedai (Yasumatsu), H. nanseiensis, n. sp. and H.macilentus, n sp.Three species removed from the Japanese fauna are as follows: C. (Colletes) kudonis Cockerell, C. (Colletes) laevifrons Morawitz and H. bridwelli, new name = H. gnathylaeoides Bridwell, 1919.The terminalia which are characteristic of the species are figured. Variation (only in the species of Hylaeus), flight records, floral records and the distribution maps are presented. Flight and floral records are summarized in figures and tables.The Japanese names for the family, subfamilies, genera, subgenera and species are wholly revised