In one embodiment, a charged particle beam writing method is for writing a pattern in a writing area on a substrate by irradiating a charged particle beam onto the substrate while moving the substrate to write stripes sequentially, each of the stripes having a width W and shapes obtained by dividing the writing area by the width W. The method includes performing S times (S is an integer greater than or equal to two) strokes, each of the strokes which is a process writing the stripes in a multiplicity of 2n (n is an integer greater than or equal to one) while shifting a reference point of each of the stripes in the width direction by a preset stripe shift amount and changing a moving direction of the substrate for each of the stripes, and writing while the reference point of the stripes in the each of the strokes in the width direction of the stripes is shifted by a preset stroke shift amount in each of the strokes.