A method of adjusting a charged particle optical system in a charged particle beam apparatus provided with the charged particle optical system including an aberration corrector in which multipole elements disposed in three or more stages and transfer optical systems are alternately disposed. The method includes adjusting aberration using at least two of the multipole elements without using at least one of the multipole elements, and adjusting parameters of the charged particle optical system other than aberration using at least one of the transfer optical systems that is not disposed between the at least two of the multipole elements used.