In the case of measuring a pattern having a steep side wall, a probe adheres to the side wall by the van der Waals forces acting between the probe and the side wall when approaching the pattern side wall, and an error occurs in a measured profile of the side wall portion. When a pattern having a groove width almost equal to a probe diameter is measured, the probe adheres to both side walls, the probe cannot reach the groove bottom, and the groove depth cannot be measured. When the probe adheres to a pattern side wall in measurements of a microscopic high-aspect ratio pattern using an elongated probe, the probe is caused to reach the side wall bottom by detecting the adhesion of the probe to the pattern side wall, and temporarily increasing a contact force between the probe and the sample. Also, by obtaining the data of the amount of torsion of a cantilever with the shape data of the pattern, a profile error of the side wall portion by the adhesion is corrected by the obtained data of the amount of torsion.