PURPOSE: To shaving-finish an internal or external gear by installing a gear shaving attachment onto the cutter holder of a boring and turning mill.

CONSTITUTION: A shaving cutter 3 is installed at the top edge of the cutter main spindle 2 of a holder 1, and said holder 1 is fixed onto a holder base 4 by a fixing bolt 5. Further, the base 4 is fixed onto an installed machine, and the amount of feed provided onto the installed machine can be transmitted to the cutter 3 at the top edge of the holder 1. Then, a worked gear 6 fore-worked through hobbing work or by a gear shaver, etc. is fixed onto a table, and meshed with the cutter 3. If the installed machine is a machine tool equipped with a mechanism for revolving a table and for feeding a cutter, all the installation is permitted, and shaving work is permitted, independently of internal or external gear or the presence of twist of tooth trace.