A charged particle beam writing apparatus includes a unit calculating a total charge amount of charged particle beams irradiating each minimum deflection region in deflection regions having different deflection sizes respectively deflected by deflectors of a plurality of levels for deflecting charged particle beams, a unit calculating a representative temperature of the each minimum deflection region based on heat transfer from other minimum deflection regions having been written before the each minimum deflection region is written, a unit inputting a first dose of a shot of each charged particle beam irradiating the each minimum deflection region, and modulating the first dose by using the representative temperature of the each minimum deflection region, and a unit including the deflectors of a plurality of levels and writing a pattern in the each minimum deflection region with a second dose, which has been modulated, by using the deflectors of a plurality of levels.