The purpose of this study is to estimate the required number of yard tractor on port container terminal. The number of yard tractor is the bottleneck factor on the efficiency of container terminal. Due to the change in travel speed and travel distance, the efficiency is difficult to estimate. The efficiency of yard tractor is estimated by the proposed simulation model that developed considering the queueing network between container crane and transfer crane. The number of yard tractor per container crane is estimated by the alternative analysis. And to determine the number of yard tractor per container crane, the performance measure such as the distance between berth and yard, the speed of yard tractor are simulated.