Recent progress in information. technology opens large possibility of production highly adaptive to end users. Further, in Japan, we have unique production, platforms called 'industrial accumulation' which is accumulation of thousands of small factories in a region. The industrial accumulation supports Japanese production of high quality, small lot size, and short delivery time. The authors are investigating participatory production where end users participate in production through collaboration with the industrial accumulation. in Suwa-Okaya area of Japan. This paper discusses issues in informatics for such participatory production. We are studying the issue through case study so as to construct field-oriented methodology and information technology that supports participatory production.