This presentation introduces the first DDI-based data catalog constructed in Japan, the “Japan Data Catalog for the Humanities and Social Sciences” (JDCat). It started its full operation in November 2021. In 2018, the Japan Society for the Promotion of Science (JSPS) initiated a five-year project to create a federated data catalog enabling data search through a single point of entry across research institutions. The National Institute of Informatics provides technical expertise to JSPS. In building a federated data catalog, we studied the practices of major data archives in North America and Europe and developed a metadata scheme for JDCat based on the DDI Codebook. Some of the controlled vocabularies are translated from DDI and CESSDA. Four social science institutions were selected through a competitive tender and were later joined by a major humanities institution. As the first institution to adopt DDI for its data catalog, we created a manual and developed an interface to edit metadata. We also created a guide for researchers new to data sharing. Metadata will be provided in Japanese and English for social sciences datasets. To integrate research data from diverse academic fields, the DDI-based metadata scheme is mapped onto the metadata scheme of the Japan Consortium for Open Access Repository for crosswalk purposes. JDCat itself is a catalog of metadata. The five institutions are responsible for preserving and disseminating data and may maintain their own catalogs. JDCat harvests metadata through OAI-PMH from the social science institutions, and through Resource Sync from the institution in the humanities. After searching the data on JDCat, users are transferred to the local catalogs for data access. Open data, such as tabular data and historic documents, can be downloaded without registration, but registration is required for survey data retrieval.