Disclosed herein is an image forming apparatus. The image forming apparatus includes a fixing device configured to fix a visible image transferred on a printing medium, a decurl device configured to correct a curl produced on the printing medium, a discharging device configured to discharge the printing medium to a space outside of a main body of the image forming apparatus, and a guide device disposed between the fixing device and the discharging device. The guide device guides the printing medium around the decurl device when a transport direction of the printing medium is reversed for duplex printing.