To easily and suitable execute a processing for combining image data for plural pages obtained by continuously reading the front and the rear surface of plural originals one by one as if the front and rear surfaces of the originals are continuously read.

The originals which are read by a reader are stored in the memory area Ma of a storage means with image data on the faces of the originals N1-Nn as first image data A1-An. Image data on the backs of the originals N1-Nn are stored in the memory area Ma as second image data B1-Bn. A filing processing for setting data as both face data is executed by sequentially copying data in a memory area Mb. Data are combined as if the front and rear surface of the originals are continuously read.