The goal of this paper is to construct a process diagnostic system of the MEMS device based on this "Large Scale Integrated (LSI) Diagnostic system" and then to perform a structural evaluation of the devices based upon the data. The paper explains the methods of analysis for the assembly process and the wafer process. The evaluation of the wafer process indicated that changes were required for MEMS devices vs. conventional LSI diagnosis. It was confirmed that "a peculiar inspection point to MEMS", "Sample making technology", and "Judgment criteria of the defect" were necessary. It is also necessary to do preliminary studies of each MEMS device and to restructure the inspection menu corresponding to the structure based on the inspection results.