The purpose of this paper is to explain the wooden roof truss of the first provisional Diet Building built in 1890 in Japan and to reconstruct it, referring to pictures (colored woodblock prints, copperplate prints and the like) of the provisional Diet Building and to other examples with similar construction in Japan and Germany. The roof truss used in the provisional Diet Building was called the "German roof frame" at that time in Japan and was a composite construction reinforced with iron tie bars. We can find several parallels in festival halls of those days in Germany. The reason seems to be that both of them were temporary buildings which had to be built in a short period.
