Charged Particle Beam Apparatus and Control Method for Charged Particle Beam Apparatus

A charged particle beam apparatus for scanning a specimen with a charged particle beam and acquiring a scan image. The charged particle beam apparatus including: an optical system that includes a pulse mechanism for illuminating the specimen with pulses of the charged particle beam, and a deflector that deflects the charged particle beam and scans the specimen with the deflected charged particle beam; and a control unit that controls the optical system. The control unit controls the optical system so as to satisfy T = n × t (n is a natural number). T represents a dwell time of the charged particle beam in each pixel of the scan image, and t represents a cycle of pulses of the charged particle beam.