Fracture stress of soybean curd was measured at temperatures between -20 degrees C and -196 degrees C by compression tests. Fracture stress increased as the temperature decreased until it reached a characteristic temperature; below this temperature the fracture stress was constant. Fracture stress varied with the moisture content of the sample measured before freezing; the lower the moisture content, the higher the fracture stress. We attempted to analyze the fracture stress of the frozen soybean curd using a mathematical model in which frozen soybean curd was regarded as a two-component system consisting of pure water ice and concentrated amorphous solution (CAS). Since the volumetric fraction of pure water ice in the system is required for the analysis, the degree of freezing of soybean curd with varied moisture content was estimated as a function of temperature using a hypothetical phase diagram for soybean curd. Based on these data, fracture stress of CAS was calculated using a series model and a parallel model. The calculated fracture stress of CAS was found to be a unique function of temperature and independent of moisture content before freezing.