An image forming apparatus includes a document reader, a storage for storing image data, an image output unit and a control unit. The control unit includes: a function setup controller for setting up the image output conditions of output images; and a control-unit side controller having a function of displaying a function setup screen corresponding to the function setup controller, on a display panel. The function setup controller has an additional input mode having a function of reading documents a multiple number of times to form multiple sheaves of documents. The additional input mode includes: an individual setup function of setting up individual image output conditions for each sheaf of documents and an all-in setup function of setting up identical image output conditions for all sheaves of documents. When the additional input mode is set up, the control unit-side controller offers a display of a setup change suggestion of the image output conditions for the next input on the display screen at the stage where the first image data input has been completed.