A first coordinate system CA of the hand unit, a second coordinate system CB of the first workpiece, and a third coordinate system CC of a second workpiece in a camera coordinate system are calculated (S2, S3, and S4). First and second coordinate transformation matrices ATB and ATC are calculated (S5 and S6). Coordinate data of a target point is set in the coordinate system of the first workpiece (S7). Coordinate data of an instruction point is set in the coordinate system of the second workpiece (S8). The coordinate data of the target point is subjected to coordinate transformation using the first coordinate transformation matrix ATB (S9). The coordinate data of the instruction point is subjected to coordinate transformation using the second coordinate transformation matrix ATC (S10). Operation instructions are generated using the converted coordinate data (S11).