[Purpose/significance] Based on the information of institutional repositories in Japan which have been collected and studied, this paper makes research on the present situation about the socialized application of institutional repositories in Japan. [Method/process] By the literature investigation, the author visited different sites of institutional repositories, libraries and databases of universities, as well as the sites of National Institute of Informatics to research the relationship between institutional repositories and other databases. [Result/conclusion] Based on the analysis, the socialized application of institutional repositories in Japan is known and this paper discusses it from four views: self-localization, data format, OAI-PMH protocol and system interoperability.