A lot of relics were unearthed in the Shinchang-dong wetland site, which can help restore prehistoric life style, including construction tools such as wood doors, wood hammers, ax handgrips, sickle handgrips, wedges, awls, wood pillars and connection members, food vessels made of earth or wood and fish, shell fish, seeds and remains of weapons. In particular, a door was found in the site, which was measured at 110cm long and 37cm wide. If restored it will be 75cm wide. The door seems to date back as far as the 1st century B. C., which would be the oldest one ever discovered in Korea. This paper is intended to explore the implications of the door by investigating the environment of the Shinchang-dong wetland site bearing the relics intact, manufacturing techniques and times of manufacturing of the door as well as attributes of doors presented in the literature related to old time architecture such as Goguryeo tomb paintings and house-shaped vessels. It also intends to provide basic data for study of residential architecture in prehistoric times.