PURPOSE: To provide the control method for suppressing vibration of the arm of the robot device.

CONSTITUTION: This control method for the robot device which has motor parts 3 and 4 and arm parts 1 and 2 suppresses the vibration of the arm parts 1 and 2 by finding a state equation as to the motor parts 3 and 4 and arm parts 1 and 2 by regarding the angles of rotation of the output shafts of the motors 3 and 4 and the angular speeds of rotation of the output shafts, and load torque as state variables, finding a state equation as a singular perturbation system using fine parameters by introducing a conversion matrix in the state equation, finding a state equation as a degeneration system by setting the fine parameters in the state equation of the singular perturbation system to zero, finding an observer of full order for estimating the angle, of rotation and angular speeds of rotation of the arm parts 1 and 2 corresponding to the degeneration system, and feeding back the angles of rotation and angular speeds of rotation of the arm parts 1 and 2 estimated by the observer.