A system manufactures a product by bending a sheet material includes a three-dimensional stereoscopic diagram creator that creates a three-dimensional stereoscopic diagram, including a desired bending angle and a desired flange width, based on graphic information of a product. A displayer displays a bending angle value in the vicinity of a bending angle, and/or a dimension value in the vicinity of a flange, in the created three-dimensional stereoscopic diagram. A test piece displayer displays a test piece of a material proposed for use in the product and displays the bending angle value(s) in the vicinity of the bending angle(s), and/or the dimension value(s) in the vicinity of the flange(s), of the test piece. A measuring device measures the bending angle value(s) and the dimension value(s) for the test piece bent by the bending machine. A calculator that calculates a stroke value using a difference between the desired bending angle and the measured bending angle, and/or a back gauge value using a difference between the desired flange dimension and the measured flange dimension.