An image forming apparatus performs a single-side image formation such that, when a delay is needed, a stacked sheet discharge control section controls a sheet carrying mechanism so that: a first sheet (for a second imaging job) to be discharged after passing a first sheet-discharging roller via a first sheet-carrying path is directed to another carrying path without being discharged, and is stood by therein. The first sheet and a second sheet (for the second imaging job) which is carried to the first sheet-discharging roller via the first sheet-carrying path after the first sheet, then are concurrently discharged overlappingly. This eliminates needs for delaying image formation for the second imaging job, and for securing time for post-process for the first imaging job. Even if a delay is inevitable, this reduces the delay time greatly and improves the productivity of the image forming apparatus, without reducing its performance wastefully.