This paper aims to clarify the process of transition in framing system of vernacular farmhouses in Tsukuba City. Analyzing the arrangement of structural columns including Okama-bashira and Daikoku-bashira, and also checking the composition of columns and beams, it's clarified that the frame has not simply shifted from Okama-bashira with lower beams to Daikoku-bashira with tall structural Kamoi named Sashi-gamoi. Okama-bashira originally acted structural base to obtain wide area including earthen floor and living space. Adopting Daikoku-bashira frame in the main living space, Okama-bashira frame still remained, however it placed far from Daikoku-bashira and exclusively acted to expanding the earthen floor.
