PURPOSE: To provide an exposure data originating device capable of originating stable exposure data.

CONSTITUTION: An exposure data originating device has CPUs 1 to 12. The CPU 1 performs region dividing process by which a plurality of partial area data 22a to 22c consisting of data about a plurality of regions divided from one another at different dividing positions are originated from layout data 21. Next, the CPUs 1 to 12 perform parallel processing, and subject data about the plural regions in partial region data 22a to 22c to conversion processing to originate converted data 23a to 23c that are obtained by synthesizing the results of the conversion processing for each of the partial area data 22a to 22c. The CPU 1 then ORs the converted data 23a to 23c and outputs the results as exposure data 24.