To operate a robot without performing teaching again even in the case of moving a jig by recognizing the present posture of the jig based on the detection value of a sensor and converting teaching data to data suited to the present posture.

A measuring hole is opened in a vertical direction so as to automatically recognize the posture of the jib after moving on the jig and the sensor composed of upper part sensors 26A-26D, lower part sensors 27A-27D and a bottom part sensor 28 is inserted to the measuring hole. A robot posture recognition part 36 recognizes the present posture of the jig based on the detection value of the sensor. Then, a teaching data conversion part 34 obtains deviation with the posture of the jig before the moving from the present posture of the jig recognized by the robot posture recognition part 36, prepares coordinate transformation data for compensating the deviation and corrects the teaching data used at the time of the play-back of the robot based on the coordinate transformation data.