1. A charged particle beam projection method comprising: (a) preparing pattern data for defining a plurality of patterns which are to be formed in a resist film; (b) assigning an exposure dose for exposing the pattern to each of the plurality of patterns; (c) approximating a deposition energy distribution when a charged particle beam is made incident upon the resist film, by a sum of a plurality of element distributions, each of which is represented by a Gaussian distribution; (d) defining a pattern area density map, partitioning a pattern layout plane on which the resist film is to be formed into a plurality of small regions, with respect to each of at least some element distributions among the plurality of element distributions; (e) repeating sub-steps (e1) and (e2) with respect to each of the pattern area density maps, (e1) obtaining an area density with respect to each small region, the area density indicating a ratio of an area occupied by the pattern disposed in the small region on the pattern layout plane to a whole area of the small region, for the pattern to be formed in the resist film, and (e2) calculating a corrected area density representative of a deposition energy to be given to the target small region when the patterns are exposed at the exposure dose assigned thereto, and assigning the corrected area density calculated to every small region; (f) calculating the deposition energy at an evaluation point on the pattern layout plane, from the corrected area density calculated in the sub-step (e2); and correcting the exposure dose assigned to the patterns based on the deposition energy calculated, and exposing the resist film to an electron beam based on the pattern data and the exposure dose corrected, and developing the resist film.