A multi-charged particle beam writing apparatus according to an aspect of the present invention comprises: an irradiation time calculation circuit to calculate an irradiation time of a beam to each pixel, for each of a plurality of pixels which are obtained by dividing a writing region of a target object and each of which serves as an irradiation unit region per beam of multi-charged particle beams; a gray-scale value calculation circuit to calculate, for each pixel, a gray-scale value of gradation by gray scale levels by dividing the irradiation time by a quantization unit; and a gray-scale value correction circuit to correct, for each of a plurality of groups each composed of adjacent pixels, dose errors each caused by gradation, by gray scale levels, of the irradiation time which occur in the adjacent pixels in a group concerned, by increasing or decreasing the gray-scale value of at least one pixel in the group concerned by 1.
MULTI-CHARGED PARTICLE BEAM WRITING DEVICE AND MULTI-CHARGED PARTICLE BEAM WRITING METHOD