The present study investigated the biomechanical effects of weight variation for side loaded carriage during walking upon joint moments and the center of body mass by using the inverse dynamic analysis. The motion data which were used as input data for inverse dynamic simulation were measured by the 3D motion analysis system. Six infrared cameras and two force plates were utilized and thirty nine reflective markers were attached to the subject to capture the walking motion with side loaded carriage. The healthy male subjects were participated in the experiment, and they walked with side loaded carriage which weighs 0, 5, 10 and 15kg, respectively. For each walking, the weight of side loaded carriage was selected randomly. As a result, the COM(Center Of Mass) was more inclined to the opposite side of side loaded carriage as the weight increased. This is the result of the balance mechanism of human in walking with side load. In other words, the human kept the total balance, leaning to the side of unloading when the human walked with one heavy side loaded. In addition, the ankle plantar-flexion moment of loading side was larger than that of unloading side when the weight increased. In knee joint, the knee extension moment of unloading side was smaller than that of loading side when the weight increased. The magnitude of hip extension moment had no significant difference. The hip extension moment of loading side was larger than that of unloading side. These results showed that the human used the ankle and hip joint of the loading side to support the body and the knee joint of the unloading side to progress the walking with keeping the balance of the body.