Shaping offset adjustment method and charged particle beam drawing apparatus

A charged particle beam drawing apparatus, comprising:

• a drawing unit configured to draw a pattern on a workpiece placed on a movable stage by deflecting a charged particle beam using a deflector;
• and
• a controller including a deflection controller configured to control deflection of the charged particle beam, a detector configured to measure a current value of the charged particle beam by using a Faraday cup provided on the stage, and a control calculator configured to control the deflection controller and the stage controller, wherein
• the control calculator includes a determination unit configured to receive information on the current value from the detector and to determine how many times the charged particle beam is already shot, and
• an operation unit configured to calculate coefficients of a cubic polynomial by applying a relationship between a size of the overlap area of the first and second shaping apertures and the current value to the cubic polynomial based on the information on the current value.