Good meat-like extrudates were manufactured from full fat soybean flour using a twin-screw extruder. From the results of FT-IR analysis, no noteworthy new chemical bonds were present in the formation of the matrix, and deamidation was observed. From the results of flow double refraction analysis, viscosity measurement, FT-IR analysis and sodium dodecyle sulfate polyacrylamide gel electrophoresis, the S-S bond did not play an important role on the formation of the matrix, and a large number of molecules in the products had a reduction in molecular weight and shifted to chain structure. It was considered that the matrix was formed by entanglements of linearized proteins and ploysaccharides in soybeans by shearing into the materials molten by high temperature and high pressure in the presence of water.