Abstract: A charged particle beam writing apparatus includes a unit to divide a chip region into first data processing blocks, a unit to, in each block, extract a cell whose reference position is located in the block concerned from cells each including at least one figure pattern, a unit to, for each block, generate a first frame that surrounds the block concerned and the cell extracted, a unit to, for each first frame, divide the inside of the first frame concerned into mesh regions and calculate an area density of a figure pattern in each mesh, a unit to combine area densities of mesh regions which are overlapped with each other and between different first frames, a unit to calculate a dose of beam by using the area density, and a unit to write a pattern on a target workpiece by irradiating the beam of the dose calculated.