An image forming apparatus includes an image forming unit configured to form an image on a recording medium, side plates extending on one end and another end of the image forming unit in a vertical direction thereof and configured to support the image forming unit, a main board including an element on a first board and fixed to the side plate on the one end such that the first board vertically extends on an outer side of the side plate, a sub-board including an element on a second board and electrically connected to the main board, a top surface member arranged above the image forming unit and including a sheet discharge tray, and a holding member configured to support the sub-board below the top surface member such that the second board extends in a direction intersecting with a plane on which the first board of the main board extends.