PURPOSE: To provide a scanning device enabling a reference model to be scanned with high accuracy during copying.

CONSTITUTION: A reference model 11 for copying is contacted and held by the holding ends 10a, 10b of a first holding portion 2 and by a second holding portion 9 rotatably provided in opposition thereto and having two ends, so that relatively large elastic deformation of the reference model 11 due to pressure when contact scans are made with a disc 13 is suppressed. The disc 13 is provided with a radial groove for accommodating the second holding portion so that no unscanned portions are left behind when areas around the point of contact between the second holding portion 9 and the reference model 11 are scanned. In copying whereby the reference model 11 is directly copied, the rotation of the first holding portion 2 is transmitted to a workpiece holding device via bevel gears 6a, 6b and a shaft 7 and the workpiece is machined by a rotating grinding machine having the same dimension as the disc 13 and moving in a manner similar to the disc.