Ion milling device and ion milling processing method

An ion milling processing method comprising:

• a cross section producing step of, by shaking a sample table about a tilt axis, which is perpendicular or substantially perpendicular to an optical axis of an ion beam emitted from an ion beam source, to shake a processing target surface of a sample that is held on the sample table and is partially shielded from the ion beam by a mask, along a plane that is perpendicular to a plane defined by the optical axis of the ion beam and the tilt axis, producing a processing target surface of the sample that is defined by the mask and is along the optical axis of the ion beam;
• and
• a smoothing step of smoothing thread-like projections/recesses produced on the processing target surface of the sample by execution of the cross section producing step by shaking the sample held on the sample table about an axis that is perpendicular to the plane defined by the optical axis of the ion beam and the tilt axis along the plane defined by the optical axis of the ion beam and the tilt axis, between a surface state in which the processing target surface of the sample faces the tilt axis direction and is along the optical axis direction of the ion beam and a surface state in which the processing target surface of the sample is tilted in the optical axis direction of the ion beam toward the ion beam source side and in which the processing target surface of the sample crosses the optical axis of the ion beam at a low angle.