PURPOSE: To shorten the time for grinding by increasing the contact area of the screwed surface of a hone with each tooth surface of a gear to be processed, and to enhance the life by preventing thereby breakage of the thread.

CONSTITUTION: Grinding layer 25 and an abrasive supporting layer 23 of a screwed hone are made of a material with elasticity, where the grinding layer 25 shall be softer than the supporting layer 23. Each abrasive grain protruding from grinding layer 25 during grinding is embedded in a binder, and the grinding layer 25 itself deflects while deforming the supporting layer 23 concavely according to the configuration of the tooth surface B. Therefore the contact area of the screwed surface A of the hone with each tooth surface B of a gear to be processed W is enlarged, and honing of the gear W can be made with high precision for a short time.