A charged particle beam pattern forming apparatus, includes a charge amount distribution calculation unit configured to calculate a charge amount distribution charged by vertical incidence of a charged particle beam on a pattern forming region of a target object; a position correction unit configured to calculate, using the charge amount distribution charged, a corrected position of each pattern forming position corrected for a misregistration amount including a misregistration amount dependent on a deflection position where the charged particle beam is deflected, the misregistration amount caused by an amount of charge; and a pattern generator configured to form a pattern in the corrected position by using the charged particle beam.