PURPOSE: To provide a layout designing apparatus capable of extremely rapidly and accurately composing.

CONSTITUTION: The layout designing apparatus comprises memory means (RAM 2 and hard disk 5) for storing first raw material data and a plurality of second raw material data corresponding to the first raw material data, layout data generating means (CPU 1) for combining the second raw material data to generate the layout data for specifying the print content of each page unit, and updating means (CPU 1) for automatically altering the second raw material data when the first raw material data is altered to update the page containing the second raw material data of the layout data.