To high accurately polish circularity, cylindricity and a diametric mutual difference of a round bar product of rotary machine main shaft, roller for roller bearing, rolling unit for a needle bearing, etc.

In a lapping polishing machine, a round bar 1 as workpiece is made to rotate around on a radial surface of a rotary surface plate 2, in a peripheral location A or internal peripheral location B of the rotary surface plate 2 where the direction of rotation of a load surface plate 3 is equal to the rotary surface plate 2, by generating a rotational peripheral speed of the load surface plate 3 faster than the rotary surface plate 2, while always forcing rolling force of rotating on its own axis in one direction to the round bar 1, by polishing, the round bar of good circularity and cylindricity is obtained. By repeating rearrangement in a carrier 5 of the round bar 1, a diametric mutual difference can be made approximate to 0.