Seitogakusha, located on Miyake Island, is an architecture constructed of 5,000 railway sleepers built in 1980 by a group with no architectural background. It awarded the Architectural Institute of Japan Award in 1981. This research attempts to grasp Seitogakusha's design drawings and the design approach given by Architect Takasuga Susumu via gathering and analyzing existing architectural drawings (1976). The following points were revealed. (1) The shape of buttress (Hikaekabe) is related to the wall amount calculation. (2) The size of sleepers derives the architecture module and is delicately linked to the construction method.