When restore the lacerated historic textiles, mostly the textiles of present day are used to support and protect them. The performance and the average life expectancy of the restored textiles are dependent on the conformity between the two textiles (historic and supporting textiles). So the selection of the supporting textiles is very important, but mostly the selections are done by only touching by hands and decided without reliable standard data. In this research, we aimed to clarify the conformity between the historic and supporting textiles by their stiffness. At the first step, we developed the new method of measuring the textile stiffness, and measured 127 silk textiles of different eras, and compared the data with heart-loop method of JIS-L-1096 and confirmed the validity of this new method (Bending Curve Test). From the results, we clarified their characteristics (thickness, weight, density, weave) and stiffness data of Kosode fragments of the Edo era, Kimono fragments after the Meiji era and several supporting silk fabrics quantitatively. The stiffness of silk fabrics varied depending on their weaving, and Kosode Fragments in the Edo era were thinner, softer and lighter compared to those of Kimono fragments after the Meiji era.