A charged particle beam writing apparatus and a charged particle beam writing method capable of shortening the time necessary to generate shot data and improving writing throughput. A graphic pattern defined in write data is divided into graphics represented in shot units. The divided graphics are temporarily stored in a memory and are distributed to their corresponding subfield areas while developing position information defined in a state of being compressed to write data. When each pattern is written by multi-pass writing, graphics divided at a first pass are used for distribution to subfield areas after a second pass.