A charged particle beam apparatus includes: a correction image acquisition part 52 for making a detector 20 acquire items of two-dimensional image data at different focal positions; a directional differentiation operation part 53 for obtaining directional derivative values in a plurality of directions for each of the items of two-dimensional image data at different focal positions; an aberration parameter calculation part 54 for obtaining aberration parameters according to previously determined methods by using the directional derivative values in a plurality of directions for each of the items of two-dimensional image data; an aberration correction value calculation part 55 for obtaining correction values for aberrations by using the aberration parameters; and a control part 56 for setting the correction values in a correction optical system control means to make an aberration corrector 16 correct the aberrations.