We formulated a flow and a rule for digitizing historical documents as organizations, not individuals or projects. It is the rule for supplying data, not going to disappear even when projects that create data will end. The flow consists of following processes: the flow has investigating materials and shooting by digital camera, screening and sorting of images, data registration into the database, image registration, security setting. Each process has a responsible person or department in our institution. As a result, images of historical materials of pre-modern Japanese history are acceleratingly concentrated in our storage, and it is growing as "image cloud for Japanese historical material". In order to further develop it, now we have been embedding function of the digital preservation[2] like an Open Archival Information System (OAIS)[3] into our system.