PURPOSE: To perform honing work by rotating for example a gear to be machined and a gear-shaped grinding wheel relatively.

CONSTITUTION: A spindle body 6 equipped with a fixed center 9 is made free of reciprocation by a reciprocating cylinder 12, while a mobile quill 7 being supported by a tail stock body 4 whose height can be adjusted by a position adjusting means 3 and besides being equipped with a mobile center 8 is pressed to the side of the fixed center 9 at always fixed pressure by a balance cylinder 25. The honing work is made by holding the axis of the gear W to be machined with the mobile center 8 and the fixed center 9, and engaging it with the gear face of the inner-gear-shaped grinding wheel 11 thereby rotating both.