To provide an image reading apparatus inexpensively by generating read image data subjected to image conversion processing applied to each of surface and backside images in real time in conformity with the relationship between the front side image and the rear side image of a double-side original.

The image reading apparatus is provided with: a scanner 70 for reading the first side of the original; a CIS 50 for reading the second side of the original; a control panel 85 for receiving designation of the relationship between the first and second sides; and an image processing apparatus 80 for applying image conversion processing to either or both of image data of the first side read by the scanner 70 and image data of the second side read by the CIS 50 on the basis of the relationship between the first and second sides entered from the control panel 85.