To evaluate the quality of the cross section of Ni alloy thin plate cut by laser, we have proposed an analysis method using SEM image to measure surface roughness of cross section. The surface roughness of the cut area of the thin plate is considerably difficult to analyze using conventional measurement technique such as profile measurement with a probe. When the SEM image is used, the roughness value can be collected quantitatively while judging the surface status qualitatively. A Hastelloy C-276 thin plate with a thickness of 50 μm coated with HTS was cut by Nd:YAG laser, and the state of the cross section was analyzed by applying the proposed method in this research. The optimum laser cutting process condition could be found for the lowest surface roughness.