Now we are attempting to apply non destructive analysis from evaluation tests or failure analysis to acceptance tests or production tests. Needless to say non destructive analysis has an advantage of conserving the state of samples and the reducing the time of analysis as compared to conventional methods with destructive physical analysis. Moreover, we are paying attention to the following reasons for nondestructive physical analysis. It is difficult to keep the reproducibility of the analysis because of the high skill level required for destructive physical analysis. On the other hand, high reproducibility can be easily achieved by fixing the condition or parameters of the device during nondestructive analysis when performed by tools like X-ray. Moreover, we expect that neither the analytical result nor the quality of the nondestructive analysis depends upon the worker's capability. In this paper we will discuss the following two items from the viewpoint of quality assurance. 1. The method of the screening for fake parts (1) The procedure flow for the production discontinued parts (2) The comparison and examination between the diagnostic using X-ray computed tomography (X-ray CT) images and various examinations (3) Other observation cases using X-ray CT images 2. Effectiveness and consideration in reliability evaluation test using X-ray CT image (1) Comparison of observation cases with a variety of jointing points in parts (2) Consideration of application of nondestructive observation technique in reliability test Use of X-ray CT images is effective in diagnosing the quality of the product or the process. Moreover, we find that use of X-ray CT images is effective for the improvement of the reproducibility of the evaluation examination. Then we find that use of X-ray CT images can reduce the time of evaluation examination too.