An image input/output control apparatus includes a control device for controlling input/output of image data with an external apparatus, plural image processing devices for performing predetermined image processes to the image data, and plural data transfer devices for connecting each of the plural image processing devices and the control device like a ring and performing data transfer among them. The plural image processing devices and the control device are composed respectively on different units, whereby the structure of the apparatus can be easily changed, and a decrease in processing speed due to the competition for buses can be reduced without increasing the number of parts necessary for bus control.