PURPOSE: To provide a lapping device whereby improved productivity can be expected by improving accuracy of machining of a cylindrical internal diametric surface of a workpiece to obtain the internal diametric surface of high quality.

CONSTITUTION: A device has a head stock 10 of drive rotating a workpiece provided on a base stand 2 to have an internal diametric surface Wa serving as a machined part, lapping head part 40 provided with a lap arm 47 moved between an operation position of pressing a polishing tape T to the internal diametric surface Wa of the drive rotated workpiece W and a refuge position separated from the internal diametric surface Wa and a polishing tape rewinding device 50 of collecting the polishing tape T supplied from a delivery reel 23 to the lapping head part 40.