Disclosed is a scanning charged particle beam apparatus equipped with an aberration corrector, contrived to eliminate resolution degradation in tilt observation by a chromatic third-order aperture aberration without relying on a specific optical system. A controller of the scanning charged particle beam apparatus provides a chromatic third-order aperture aberration measurement method relevant to tilt observation of a specimen. Further, the controller has a chromatic aberration control function relevant to tilt observation of a specimen. By means of the chromatic aberration control function, the controller controls a chromatic aberration to be positive or negative, rather than remaining at 0, in order to eliminate an image blur which occurs in a direction parallel to the specimen surface due to a chromatic third-order aperture aberration and a chromatic aberration at a tilt angle (t1) under observation and another tilt angle (t1) axially opposite to the tilt angle.
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