In this study, I reserch Otai which is a post town of old Nakasendou in the Edo era. I analize the regional characteristics of the house plan and the townscape in the "Shukuezu"; old maps in the middle of the Edo era. As a result, the following things can be said ; relatively small houses were intensively seen both in Kamimachi and Shimomachi while rather big houses were seen in Nakamachi, each town had its own streets view, those small houses had many similarities with neighbor farmhouses in terms of the size and the house plan.
