A multi-functional peripheral allows a user to select a productivity priority mode or an image quality priority mode. In the productivity priority mode, a scanner performs a reading operation without moving first and second carriages in a sub-scanning direction, a foreign object image removing processing is executed in accordance with image data obtained by the reading operation, and image forming is performed in accordance with the image data applied with image processing. In the image quality priority mode, the first and second carriages are moved from a reading position P to a reading position P' at which the foreign object does not adhere to a reading slot, the scanner performs the reading operation, and an image forming is performed in accordance with image data applied with image processing not including the foreign object image removing processing.