This paper proposes a dynamic model for a defective production system with Poka-Yoke. Poka-Yoke is a Japanese phrase which means mistake-proofing. The technique of Poka-Yoke has been diversely applied in modern production systems. In this study, we evaluate the total cost of a defective production system with Poka-Yoke. We also use a practical case in automotive industry to verify the proposed model. The case study reveals that Poka-Yoke is a cost-effective mechanism that generates satisfactory return of a defective production system, the effect of which depends on the investment cost of Poka-Yoke.