1. A charged particle beam drawing apparatus, comprising: a drawing unit including a charged particle source, a deflector and a stage on which a target object is placed, to perform drawing with a charged particle beam on a plurality of drawing regions on the target object; and a calculator to calculate a drawing progress ratio on the target object using a ratio of a drawn area of the drawing regions to a total area of the drawing regions, wherein the calculator determines whether an estimated number of the drawing regions and an estimated number of shots of the charged particle beam are acquired, and when it is determined that both the estimated number of the drawing regions and the estimated number of shots of the charged particle beam are not acquired, the calculator calculates the drawing progress ratio using the ratio of the drawn area of the drawing regions to the total area of the drawing regions.