PURPOSE: To enlarge the operation zone of a multi-axis articulated robot by performing a smooth interpolation operation in the area of ≥360°, by giving a specified signal as the rotation position of the position control operation starting time so that the signal expressing the rotation position of after rotation of an axis may become in the range of ±360° for the reference position of the axis.

CONSTITUTION: The data of ≥±360° are given as the present value of a 6th axis by its multi-rotation (step 50). In this case, whether the present value of the 6th axis is corrected or completed as it is without any correction is decided by whether the succeeding operation is an interpolation operation or not (step 51). Now, in case of the succeeding operation being the interpolation operation, the process of correcting the present value data of the 6th axis at ≤±360°C is carried out (step 52). Namely, the interpolation operation is started after giving that which subtracts the signal of the rotations equivalent to the number of rotations expressed by the integer from the reference position of the axis from the rotation position signal of after rotation of the axis, and a smooth interpolation operation is performed in the zone of ≥±360°.