A charged particle beam writing apparatus includes a unit to calculate a gradient of a convolution amount that is calculated from a convolution operation between an area density and a distribution function, a unit to calculate a small influence radius phenomenon dose correction coefficient that corrects for dimension variation due to a phenomenon whose influence radius is on an order of microns or less, by using the convolution amount and the gradient, a unit to calculate a proximity effect dose correction coefficient that corrects for dimension variation due to a proximity effect, by using a first function depending on the small influence radius phenomenon dose correction coefficient, a unit to calculate a dose by using the proximity effect dose correction coefficient and the small influence radius phenomenon dose correction coefficient, and a unit to write a figure pattern concerned on a target object, based on the dose.