Legged locomotion is high environmental adaptability by the effect of ability to choose landing positions freely. But the conventional legged locomotion machines have not been able to do high efficient legged locomotion, because most of actuator outputs are wasted to support upper body weight. In this case, the methods are pointed to be effective that compensating upper body weight by mechanical device, but it has not succeeded by this method. So, we propose it with passive gravity compensation mechanisms. First, we analyzed load shifts of legs, and it is clarified that this shifting needs two compensation mechanisms on each leg. One of the two is used to support the upper body, another is used to idle leg. Second, we develop novel two mechanisms, one of the two can change in the size of the compensation force. Another can change in the direction of the compensation force. Finally, we create the desired device by combination of those mechanisms, and measure compensation force throughout the walking motion. In conclusion, the novel system enabled upper body weight-free legged locomotion by means of using most of the actuator output for walking.