Disclosed is a shield (8, 10) disposed between an ion source (1) of an ion milling device and a sample (7) so as to be in contact with the sample. The shield is characterized by having a circular shape having an opening at the center, and by being capable of rotating about an axis (11) extending through the opening. Further, a groove is provided in the ion source-side surface of an end portion of the shield, and an inclined surface is provided on an end portion of the shield. Thus, an ion milling device having a shield, wherein the maximum number of machining operations can be increased, and the position of the shield can be accurately adjusted.