Pod-driven ships have high performance both for energy saving and for utility as stern thruster, but they also have the difficulty in designing maneuverability. It is accordingly important to estimate the steering quality indices as accurately as possible in the early stage of design. This report deals with the steering quality indices by analyzing zigzag experiments of several pod-driven ships presented in the paper by M. D. Woodward, et al. The indices obtained are summarized in the graphs using the key parameter made of strut area and the graphs indicated here will be useful in the practical design of a new pod-driven ship. As the result of the consideration, it is found that pod-driven ships have small damping moment similar to that of conventionally propelled cargo ships and tankers with rudder. Through this study, it is also revealed that increase of strut area enables improvement of course-keeping quality.