PURPOSE: To facilitate a metallic phase test by preventing the generation of the so-called 'edge droop' and the peeling off of an oxidized film on the edge part of an end surface occured by polishing in the method for polishing the end surface of a metallic phase sample, when a metallic phase test is carried out for the covered pipe, etc., of a fuel element in PWR fuel collective.

CONSTITUTION: On a round pipe shaped or a round bar shaped metallic phase sample 3, the metallic phase sample 3 is rotated around a sample axial center 3a under such state that the end surface 3c of the sample is pushed onto the surface 2a of a polishing paper 2 fixed on a stationary plate 1. Thereby, even if a step part is generated on the border between the slide surface 2b of the polishing paper 2 with which the end surface 3c is contacted during polishing and the non-wear portion on its periphery, the edge portion of the end surface 3c is not pushed to this step part. Therefore, an edge droop and the peeling off of an oxidized film are not generated.