A multi-charged particle beam writing apparatus according to one aspect of the present invention includes a region setting unit configured to set, as an irradiation region for a beam array to be used, the region of the central portion of an irradiation region for all of multiple beams of charged particle beams implemented to be emittable by a multiple beam irradiation mechanism, and a writing mechanism, including the multiple beam irradiation mechanism, configured to write a pattern on a target object with the beam array in the region of the central portion having been set in the multiple beams implemented.