robots for industrial use having an arm mechanism of a horizontal multiple articulated type . the load movement mechanism and the arm expansion mechanism , which are provided within the robot arms in advance with respect to the change condition through the catching of the gravity force changes by the force sensor from a case where the weight is moved , placed to a case where nothing is grasped , are properly operated , so that the mutual dynamic interferences of the respective driving portions of the robot may not be caused or may be made minimum , and may be made simple in shape by the comparatively simple control apparatus , with an effect that the superior robot which is capable of stable operations may be realized .