The purpose of this paper is to clarify all the processes of plans from the first design (European style), the second one (semi-European style) of the Diet Building until the building was finished as a temporary construction, the plan of which was discovered in 2004 in Chiba. The first plan of the Diet Building was designed by Paul Kohler, who worked at the architectural firm Ende & Bockmann in Berlin; the provisional Diet Building was completed by Adolf Stegmuller at the same firm and Shigenori Yoshii. Though the scale of the provisional Diet Building was reduced sharply and the construction was changed to wood from brick, with regard to the room arrangement both of the plans were very similar; accordingly, the idea of the first plan designed by Kohler, who had to retire because of his illness before completion, still existed.
