An image forming apparatus includes image forming unit, frame structure, a plurality of rotational shafts, a plurality of drive gears, resin drive housing, and high voltage substrate. The frame structure includes at least one metal side plate frame having inner side surface facing internal space that accommodates the aforementioned unit and outer side surface opposite the inner side surface. The plurality of drive gears each rotate about an axis of the rotational shaft. The drive housing includes supporting side surface that supports one end of the rotational shaft and cavity in which the plurality of drive gears is accommodated, and the drive housing is open at the other end of the rotational shaft. The drive housing includes substrate supporting portion that supports the high voltage substrate, and is attached to the side plate frame such that the opening is sealed by the inner side surface of the side plate frame.