1. A charged-particle beam writing method for deflecting a charged-particle beam and writing each pattern onto a sample placed on a stage, comprising the steps of: calculating a charge amount distribution in an irradiation region of the charged-particle beam and a charge amount distribution in a non-irradiation region thereof, using an exposure distribution of the charged-particle beam applied onto the sample, and a fogging electron amount distribution; calculating a distribution of a position displacement amount of the charged-particle beam on the sample, based on the charge amount distributions in the irradiation and non-irradiation regions; and deflecting the charged-particle beam, based on the distribution of the position displacement amount and writing each pattern onto the sample.