PURPOSE: To drastically reduce the operation quantity of the whole body by using those which delay the positional posture command and positional posture correction quantity corrected as the deviation from the present positional posture and spring center positional posture of a robot arm necessary for realizing a spring actuation more than one sampling time by a time delay element.

CONSTITUTION: A track forming part 4 which commands a reference positional posture becoming a spring center positional posture and a spring control arithmetic part 6 which finds the positional posture correction quantity for working as a spring are provided. A reference positional posture command and positional posture correction quantity are then compounded by a compound part 7 to make a compound positional posture command. A robot arm is then moved by a positional posture control part 8 according to this command. This positional posture correction quantity is timely delayed by a 1st time delay element 13 and the compound positional posture command is timely delayed by a 2nd time delay element 14. In this case, the output of the 1st time delay element is used as the deviation from the present spring center positional posture and also the output of the 2nd time delay element as the present position of the robot arm.