In order to investigate the maneuverability of tug-barge, sea trial tests such as speed, acceleration/deceleration, $10^{circ}$ turning, $20^{circ}$ turning, $10^{circ}/10^{circ}$ zigzag and $20^{circ}/20^{circ}$ zigzag were conducted with both tug and tug-barge. From the result of turning test, longer tactical diameter and lower rate of turn of tug-barge than those of tug are obtained. From the result of the zigzag test, bigger overshoot angle of tug-barge than that of tug is obtained. When they turned or changed a course, it showed that the barge turned inner side of the trajectory of tug. For the safe navigation, the helmsman of tug-barge should be aware of these maneuvering characteristics.