An ion milling device of the present invention is provided with a tilt stage which is disposed in a vacuum chamber and has a tilt axis parallel to a first axis orthogonal to an ion beam, a drive mechanism which has a rotation axis and a tilt axis parallel to a second axis orthogonal to the first axis and rotates or tilts a sample, and a switching unit which enables switching between a state in which the ion beam is applied while the sample is rotated or swung while the tilt stage is tilted, and a state in which the ion beams is applied while the tilt stage is brought into an untilted state and the sample is swung. Consequently, the ion milling device capable of performing cross-section processing and flat processing of the sample in the same vacuum chamber is implemented.