Social Science Japan Data Archive (SSJDA) has been developing DDI implementation projects. We present ongoing projects and some difficulties in the project. Now, users can access more than 1300 datasets and metadata, but those are not based on DDI format. We plan to make metadata in the DDI format (DDI 2.5). But we have some problems with DDI implementation projects. In particular, it is difficult to map between the controlled vocabularies in DDI and some survey methods commonly applied in social surveys in Japan. There are also differences in the granularity of metadata, such as the 'Topic Classification' element. We like to discuss these projects and these difficulties in the project with the EDDI20 participants.