An image forming apparatus including: a paper feed cassette; a paper pickup roller; an image forming portion; a fixing unit; a paper discharge portion for discharging paper P with a developer image fused and fixed thereon; and an inversion roller and a paper discharge drive roller for conveying paper P along a paper conveyance path, and is constructed such that guide ribs are provided for a curved portion in a main conveyance path and the first and second curved portions of a sub conveyance path are provided in shapes that will not cause concentration of stress acting on the paper P in abutment.