This paper presents a design and an implementation of document image retrieval to support reading mokkans. A mokkan is a wooden tablet with text written by a brush in India ink. Despite the archaeological and historical value of the mokkans excavated from ancient ruins, many of the mokkans have not been decoded yet due to the lost or too much damaged character patterns on them. Character recognition for damaged patterns is useful to decode such mokkans. Furthermore, if the recognition results show not only the character codes but also the images of the character patterns and the whole mokkans, the recognition becomes useful document retrieval to complement the lost or unreadable part of the mokkans. In the implementation, we built a public database of historical mokkans with their photographs and a character recognition module working on our support system to search the database. The evaluation by archaeologists is in progress.