In a side entry type sample holder, vibrations in the radial direction of the sample holder provoke a resolving power decrease in the measurement results. In the present invention, the side entry type sample holder has a stepped portion in the radial direction of an axial portion. The sample stage has a support part contacting the stepped portion in a cylindrical portion capable of moving as one body in the axis direction of the sample holder, and, through the contact between the stepped portion and the support part, a frictional force is generated, opposing the radial direction of the axial portion in the sample holder. In this manner, the vibrations in the radial direction of the sample holder are suppressed, and the resolving power decrease in the measurement results is suppressed.