An image forming apparatus is provided that is capable of, in displaying a preview of image data to be output, confirming a confirmation point in accordance with an operation mode immediately without performing a user operation such as enlarging, reducing or shifting. The image processing apparatus (illustrated as a digital multi-functional peripheral) is capable of operating in each of a plurality of operation modes. The image forming apparatus is provided with an image display portion such as a touch panel for displaying a preview of image data and a set value storage portion such as control memory for storing a display set value in displaying a preview image at first on the image display portion for each operation mode.