This is a system that measures the flatness of steel plates. After finishing mill in a rolling mill, it measures the surface flatness non-contact, at the front and back of the product inspection line, and plate leveler, to determine the quality. It comprises processors like the laser module and the camera module, and acquires the shape data of rolled steels by continuous 3-D shape measuring against lifting, tilting and shifting. Also, by measuring height, wavelength or pitch, waviness, and C-curve, it can be used for the purpose of quality control, and can control the Leveler.