Brittle stars are marine invertebrates that often dominate the seafloor. Their global distribution range and abundance make them useful as marine environmental bio-indicators. Despite their importance, however, there is limited availability of data on brittle star specimens in Japan. In this study, we focused on Sagami Bay, one of the oldest Japanese sea areas for the study of brittle stars, and organized the data of the specimens obtained there. This collection included specimens collected between 2005 and 2021, with a total of 738 samples, which were identified as 112 species. In this data set we ignored the duplication at each sampling site. All data are deposited in the Global Biodiversity Information Facility (GBIF) through the Japan Node of GBIF and are thus accessible through the GBIF portal under the Creative Commons Attribution 4.0 International license. The complete data set for this abstract, published in the journal’s Data Paper section, is available in electronic format in MetaCat in JaLTER at http:/++++++(Scheduled to be obtained after acceptance).