To provide a device and a method for manufacturing an extremely smooth grating stably forming a fine structure line constructing the extremely smooth grating scale used at a nanometer level or at a sub-nanometer level besides on an accurate position.

The device for manufacturing the extremely smooth grating is provided with a fine structure line forming function to form the fine structure line on a substrate 101 with a probe 2 of a contact mode scanning microscope and a length measuring function to measure the length of the nanometer level via the probe 2 and forms the pattern-shaped fine structure by alternately carrying out the fine structure line forming movement and the length measuring movement for the formed fine structure line.