Aiming for easily carrying out an energy discrimination or an angle discrimination of a secondary particle emitted from a sample or easily setting an optimal observation condition, a charged particle beam apparatus is provided with a charged particle source for emitting a charged particle beam, a lens for focusing the charged particle beam to a sample, a detector for detecting a secondary particle emitted from the sample, and an orbit simulator for calculating a position at which the secondary particle emitted from the sample arrives; and in this structure, the orbit simulator calculates an orbit of a secondary particle that satisfies a predetermined condition, and a sample image is formed by using a signal detected at a position where the secondary particle satisfying the predetermined condition arrives at the detector.