To provide a lapping tool by which accuracy of a lapping finish work can be made higher, a lifetime of the lapping tool itself can be extended, a lapping diameter can be adjusted and the lapping finish work of various diameters is available.

The lapping tool includes a lapping tool body 1 having a lapping portion on an outer circumference, and a slit 7 provided along an axial direction between an end and a base end in the lapping tool body 1. The slit has an adjusting part of a lapping diameter and a lapping adjusting part of lapping to adjust the diameter of the tool body via an adjusting member of the lapping diameter which is inserted so that it may be pulled out.