Tobacco materials are progressively damaged and broken by the external forces of manufacturing machinery and equipment throughout the entire process. Recently, with the increase in the speed of equipment, the level of tobacco materials' breakage has become higher. The only way to assess the level of breakage is to measure the mean-diameter of tobacco materials in the actual production process. Therefore, we have established a method for estimating tobacco materials' breakage in order to minimize breakage level. As previously presented at CORESTA 2003 in Freiburg, we have established a formula that can clarify material breakage under a wide range of conditions (temperature, moisture, input particle size) and identified effective parameters. Additionally, we have developed a numerical simulation of tobacco cut-rag breakage from this formula and applied a DEM (Discrete Element Method) for the modelling of cut-rag. We confirmed a high correspondence between the calculated value and experimental value for the level of cut-rag stress and the mean diameter after the breakage. This method enables us to forecast the breakage level, when external energy is added to the mass of cut-rag.