chestnuts were the main staple. Utilization of horse chestnuts showed a remarkable increase in the Late Jōmon. Horse chestnuts were found in waterlogged sites, mostly associated with wooden structures which could have been used for food processing. Japanese folklore examples of the processing of horse chestnuts show that they could have been used to obtain large amounts of nuts. Compared to folklore examples, Jōmon wooden structures are larger, which could be due to their use in a communal context. This paper examines Jōmon wooden structures and remains found within them, and then explores the potential social impact of the change in food exploitation.