A 3-dimensional form of a sample product constituted by a plurality of parts having known forms is measured by imaging the sample product from a plurality of directions. Arrangement data representing the 3-dimensional positions and orientations of the parts constituting the sample product are obtained, by a construction detecting module, on the basis of the measured 3-dimensional form of the sample product. A task planning module sets a task for moving a part to be used for constructing a product and the sequence of the task by using arrangement data acquired by the construction detecting module. Upon generation of motion command data for controlling a robot for constructing the product in accordance with the task set by the task planning module, the generated motion command is output to a motion control module. The construction robot is controlled by the motion control module, whereby a product the same as the sample product is constructed.