The primary purpose of this study was to analyze triple leg joint system for understanding the dynamic movement of legs joint in golf driver swing. For this purpose, joint torque were calculated. In order to determine the load on the left leg, a triple joint system was set for ankle, knee and pelvis, torque working on the left leg region were estimated. For this study, a total of 3 professional golfers were sampled, and then, their driver swings were recorded with 6 motion capture cameras (250 frames/sec.) to be synthesized into 3-dimensional images and coordinated. All data were calculated using workstation(VICON. Ltd) graphic program. And then, the results of this study can be summarized as follows; It was found that the joint torque was generated in the direction opposite the target on ankle and shank during down swing, while in the direction towards the target on the pelvis region. During impact and release, the torque on the knee & hip joint was converted from the direction opposite the target to the direction towards the target, while the torque on the knee joint region was generated vice versa.