Purpose: Evaluation and feedback are fundamental components in a residency program. A portfolio assessment system is an appropriate option for making formative assessments, particularly for a family medicine resident whose training includes rotations through various disciplines at multiple locations. However, a paper-based portfolio assessment system has limitations when applied to a clinical environment due to how it is managed and cared. This study assessed the satisfaction and utility of a paper-based portfolio assessment system, and then designed and implemented a web-based portfolio assessment system for family medicine residents. Methods: A self-administered questionnaire focusing on the satisfaction and utility of a paperbased portfolio assessment system was given to 23 family medicine residents. A web-based portfolio assessment system was then designed using the component-based development approach. Results: The overall satisfaction and utility with the paper-based portfolio assessment system were low. Fifteen residents (62.5%) reported that following a paper-based portfolio assessment system was sometimes a waste of time and only three (13.0%) reported having no problems. The web-based portfolio assessment system was successfully designed to be easy to implement and user-friendly. Conclusion: The web-based portfolio assessment system is expected to overcome the shortcomings of a paper-based portfolio assessment system and improve the level of satisfaction of medical residents. It is expected that the web-based portfolio assessment system designed in this study will be an additional tool for family medicine residencies.