A motion support system is important for improving the quality of life for people with inadequate muscle power for walking or standing. Such a system must maintain coordination between the movement of the living body and that of the motion support system with respect to timing and power. We have developed a preliminary assistance device for human locomotion that does not restrict movement of the user's lower extremities. To determine the appropriate timing and applied force for this assistance device, we have use two types control mode; (1) surface EMG signals from the lower limb in preliminary controller. Each assistance leg has a three-axis magnetic sensor near lower end which tracks a magnet attached to each ankle of the user's legs. This sensor attracted to a magnet attached to the human ankle in the leg swing phase. The mechanical leg supports the user's weight when the leg is in the standing phase.