In today's society, you must leave your personal data for everything. However, there is a risk of data leakage during the operation process. Therefore, many people could be cheated due to data leakage or data used by other purpose cause property loss. This study uses the Failure Mode and Effects Analysis (FMEA) method to find out the potential factors of possible data leakage in the process of the Skill Certification, and to improve these possible factors, hoping to achieve the best results. The 5W1H from Toyota way management and poka-yoke method were used to find out the true causes of personal data leakage and propose effective prevention plans.