PURPOSE: To perform the adjustment of a holding force electrically wholely, and to simplify the structure of a servohand part, by providing a changeover means which can connect a torque control means only with a position control means and speed control means being cut-off from a servomotor.

CONSTITUTION: In the case of holding an object by a holding mechanism, a position control means 6, speed control means 5 and torque control means 4 are first connected to a servomotor 2 altogether, and the object is held by a holding mechanism while performing the controls by the respective control means 4, 5, 6. Thereafter, the holding force for the object is kept in the specified value with the torque control only by the torque control means 4 being executed by changing over a switching means 8. Consequently, the adjustment of the holding force can be executed electrically altogether.