PURPOSE: To enhance stability of walking by providing a posture target value setting means constituted so that the aggregate of intersections between a polyhedron formed with parts of a robot making contact with the environment as vertexes and pressure vectors of all external forces acting on the robot is contained in a posture target value.

CONSTITUTION: According to the posture of a robot 1 or posture target value related to the time series of posture set by a posture target value setting means 26, a target operating quantity of the actuator of the robot is determined by a target operation quantity determining means 26. The actuator is driven by a driving means to attain the target operating quantity. The aggregation of intersections between a polyhedron formed with parts of the robot making contact with the environment as vertexes and vectors of the resultant force of all external forces worked to the robot by the environment is contained in the target value related to the posture or the time series of posture. Further, the target value of the aggregation of intersections is situated in the polyhedron. Thus, the stability of walking of the robot is enhanced.