An image forming apparatus includes an image forming unit having an image forming portion positioned over a partition wall that vertically partitions a body frame above a cover plate. A second circuit board in which a tall electronic component-mounting side is upward directed is placed in a space between the partition wall and the cover plate. A first circuit board in which an electronic component-mounting side is downward directed is placed on a lateral side of the second circuit board. The first and second circuit boards are placed in a stepwise manner so that the level of the first circuit board is higher than that of the second circuit board. A return path for reversely transporting a sheet is formed between the cover plate and the upper face of a return tray.