A charged particle beam impinging on a specimen is set to have left and right tilt angles corresponding to a parallactic angle. A control unit is provided which scans the beam over the specimen while giving a left tilt and a right tilt corresponding to the parallactic angle alternately to the beam on each scanning line. In this way, images are acquired. A three-dimensional image in which deterioration of the resolution is suppressed is displayed in real time by combining aberration cancellation means with the control of the beam according to the parallactic angle. The aberration cancellation means uses an optical system having plural stages of lenses to provide overall cancellation of aberrations by making use of the action of a lens to deflect the beam back to the optical axis.