Drifting behavior of a container on an apron due to tsunami run-up and drawdown is investigated using hydraulic experiments and numerical simulations. When a container and a wall on the apron are set parallel to the seawall, the container can drift to the sea for the large relative overflow height of an incident tsunami and the small relative position of the container. It is consequently suggested that it is not always effective to move containers landward before tsunami attack to prevent the containers from drifting to the sea. When a wall with an opening is set oblique to the seawall, a container parallel to the seawall can rotate toward the normal to the seawall as drifting through the opening. As a result, it is necessary to consider various drifting patterns of container in dealing with the container drifting landward through the opening.