An image forming apparatus in which an original reading portion is disposed in an upper portion of the apparatus main body, a feed portion is disposed in a lower portion of the apparatus main body, and a printing portion is disposed between the original reading portion and the feed portion as an image forming system, is configured as follows. A paper post-processing portion that can perform a plurality of types of paper post-processing for recording paper transported from the apparatus main body after printing by the printing portion is finished, and a discharge portion to which recording paper is discharged after paper post-processing by the paper post-processing portion is finished, are disposed in a space of the apparatus main body formed by the original reading portion, the printing portion, and the feed portion. The paper post-processing portion is provided such that it can slide relative to the apparatus main body. In a front face of the paper post-processing portion, a cover is provided that covers this front face. The discharge portion is provided such that it can be raised or lowered according to the quantity of stacked recording paper.