An image processing portion for conducting the specified processing of an image to be reproduced by an image forming portion based on the processed image data is constructed as a single control portion. Consequently, the development of a variety of digital copying machines requires preparation of specially designated control boards according to levels of the products. This makes machines expensive and requires users to pay a considerable initial cost. An image processing device of the present invention is provided with an image information inputting means for inputting image information as a first level image, a main image-processing board for conducting the specified processing of the input image information of the first revel image, a sub image-processing board for conducting the specified processing of the image information processed by the main image processing board and outputting the information as a second level image, and a means for reproducing an image according to the image information processed by the main image-processing board or the sub image-processing board. These boards are independent from each other in the circuit configuration.