PURPOSE: To provide permissible values to working accuracy and positioning accuracy of the works by performing the section of the amplitudes and frequencies of the AC signal from a weaving circuit disposed to a drive control circuit for the arm axes and wrist axes of the robot as well as the moving axes for applying the AC signal at arbitrary points on the weld line.

CONSTITUTION: The movement command signal 1 which has beforehand been programed to the X-axis of the arm of the robot is sent as the data for the positions requiring continuous movement into an adder 3. When the sine wave signal of a weaving circuit 2 which commands weaving operation has not entered the adder, the difference from the current position signal of (-) by a current position detector 9 is applied to a servo amplifier 4 by way of the adder 3, the moving axis keeps moving in accordance with the command signal owing to the closed loop of a servo valve 5, cylinder 6, rack 7, the pinion 8 intermeshed with the rack 7, and the position detector 9 connecting to the stem of the pinion 8. On the other hand, when the sine wave signal is added to the adder 3 from the circuit 2, the moving axis subsequently advances while making the sine wave motion of small advance and retreat by the weaving AC signal.