1. A charged particle beam lithography apparatus, comprising: a first block area divider configured to divide a pattern forming area into a plurality of first block areas in order to make a number of shots when forming a pattern substantially equal; an area density calculator configured to calculate, using a plurality of small areas obtained by virtually dividing the pattern forming area into mesh areas of a predetermined size smaller than all of the first block areas, a pattern area density of each small area positioned therein for each of the first block areas; a second block area divider configured to re-divide the pattern forming area divided into the plurality of first block areas into a plurality of second block areas of a uniform size, which is larger than the small area; a corrected dose calculator configured to calculate, using the pattern area density of each small area, a proximity effect-corrected dose in each corresponding small area positioned inside the second block area for each of the second block areas; a beam dose calculator configured to calculate, using the proximity effect-corrected dose of each small area, a beam dose of a charged particle beam in each corresponding small area; and a pattern generator configured to form a predetermined pattern on a target object by irradiating a charged particle beam of the beam dose calculated for each of the small areas.