A multi charged particle beam writing apparatus according to the present invention includes an aperture member, in which a plurality of openings are formed, to form multiple beams, a blanking plate having a plurality of blankers to respectively perform blanking deflection of a corresponding beam in multiple beams having passed through the plurality of openings of the aperture member, a blanking aperture member to block each of beams which were deflected to be in a beam off state by the plurality of blankers, a plural stage objective lens to focus multiple beams having passed through the blanking aperture member onto the target object and a plurality of electrostatic lenses, at least one of which is arranged at each stage of the plural stage objective lens, to dynamically correct defocusing of the multiple beams during writing.