Container traffic between Busan and Japan is continuously blooming as the global economy grows impressively. It is interesting to see that Busan in Korea has great potential to be considered as a transit port for container export/import in Japan instead of Japanese domestic transit ports, due to the special geographic location and economical container handling cost. This paper attempts to demonstrate the economic competitiveness of Busan port for container transshipment. It describes models for analyzing the container transportation time and cost by transshipment mode, specifically, transferring via the ports of Japan vs. via Busan. A simulation programming method is developed to build the models. A case study which considers twenty Japanese regional cities has been presented. According to the comparison of simulation results and sensitivity analysis, the paper concludes with a discussion and suggestions for the container transportation transshipment network design of Japan.