PURPOSE: To execute the polishing of an internal surface in a high accuracy, by controlling so that a polishing load becomes constant with an arm being rotated by a micro driving means according to the polishing load applied on the internal surface.

CONSTITUTION: The change of the polishing load of a polishing tool 36 to the internal surface 16a of a work piece 16 is detected by a detection means 37. Then, an arm 34 is rotated with a microdriving means 31 being driven by this detection signal. Therefore the polishing load applied on the internal surface 16a of the work piece 16 by the polishing tool 36 can be maintained constant at real time.