A phenomenon that crack was formed in the manufacturing process of Al2O3 products was analyzed with a simulation model developed in previous papers. The position of stress concentration by finite element analysis was compared with the cracked position to examine the model for its validity. Analytical results for tensile stress concentration and deformation agreed well with the actual phenomenon. Furthermore, the value of maximum principal stress analytically decreased with increasing thickness of the part at which the crack generated, and this also agreed with the actual phenomenon. A new developed FEM model for simulating the sintering process of ceramics was considered to be effective in predicting crack generation in products and in taking steps to prevent cracking.