Deformation and mechanical damage measurement techniques were developed in order to investigate the degradation process of SOFC cell/stack and module under SOFC operation. In this study, the deformation and mechanical damage test was applied to simulated cell and stack. The deformation, microcrack and delamination in the cell and stack were detected by displacement gauge and acoustic emission (AE) method. The observation method determined location of signal and mechanism of the deformation and microcrack in the SOFC cell/stack. By using this method, it was possible to show the possibility that the detailed deterioration process can be evaluated, visually, and in real-time, even when applied to cell and stack at the actual equipment level.