A positioning control system wherein variations in the robot coasting distance are substantially eliminated by stopping the command pulse signals simultaneously with a generation of the origin pulse signal from the incremental encoder. The deviation between the final robot position and the origin is minimized by driving the motor in its backward direction to back up the robot by an amount approximately equal to the coasting distance. The robot moving distance during the time period from the beginning of origin return operation (i.e., backup) to a generation of the first spike in the origin pulse signal after beginning backup to the above first stoppage of the robot is found. If the found distance is different from the coasting distance then this difference is handled as an error.In one aspect of the present invention, the number of spikes appearing in the output pulse signal from the incremental encoder can be easily increased as necessary to thereby improve the resolution power of the incremental encoder. Further, much more precise positioning control can be realized by synchronizing the output pulse signal of the incremental encoder with the clock signal of the microcomputer.